Python Interview Questions and Answers

Python is a widely-used, high-level programming language that is popular for its simplicity, versatility, and ease of learning. It is used in a wide range of applications, from web development to machine learning and data science.

In today’s competitive job market, having a strong understanding of Python can greatly improve your chances of landing a job in the tech industry. Whether you’re a recent graduate looking for your first job or an experienced professional looking to expand your skillset, knowing Python can open up a wide range of career opportunities.

In this blog, we will cover some of the most common Python interview questions you may encounter during a job interview. We will start by discussing the importance of Python in the tech industry and why it is such a valuable skill to have. We will then cover a range of topics, including Python syntax, data types, control structures, functions, object-oriented programming, and more.

By the end of this blog, you should feel confident in your ability to answer a wide range of Python interview questions and be well-prepared for any Python-related job interview.

Python Interview Questions for Beginners

The following questions test the basic knowledge of Python keywords, syntax and functions.

1. What is a dynamically typed language?

A dynamically typed language is a programming language in which variable types are determined at runtime, rather than being explicitly declared. This means that the type of a variable can change during the execution of a program. Examples of dynamically typed languages include Python, Ruby, and JavaScript.

In contrast, statically typed languages like Java and C++ require variables to be explicitly declared with a specific data type and cannot change during runtime.

The advantage of dynamically typed languages is that they offer more flexibility for developers and can make the code easier to read and write. However, they can also be more prone to errors, as the type of a variable may not be what the developer intended.

Python is a dynamically typed language, which allows for more concise and flexible code. However, it’s important to be aware of the potential risks and challenges associated with this approach.

2. Is Python an interpreted language? Explain?

Yes, Python is an interpreted language. This means that, unlike compiled languages such as C++ or Java, Python code is executed line by line, without needing to be compiled first. This allows for faster development, easier debugging, and greater flexibility.

Python code is executed by an interpreter, which reads each line of code and executes it immediately. This is in contrast to compiled languages, where the code is first compiled into machine code before being executed.

One advantage of an interpreted language like Python is that it can be run on any platform with a Python interpreter installed. This makes Python a very portable language and one that is widely used in a variety of different applications, including web development, data analysis, machine learning, and more.

3. What is Scope in Python?

In Python, a scope is a region of the program where a particular variable is defined and can be accessed. Python has two types of scopes: global and local. A global scope is accessible throughout the entire program, while a local scope is only accessible within the function or block where it is defined.

In other words, a variable defined in a certain scope can only be accessed within that scope or lower scope. If a variable is defined in a local scope, it cannot be accessed in a higher scope, such as a global scope.

It is important to understand the concept of scope in Python because it affects how you define and use variables in your code. If you want to use a variable throughout your entire program, you need to define it in the global scope. If you only need to use a variable within a specific function or block, you can define it in a local scope.

Python also has built-in functions, such as globals() and locals(), that allow you to access variables in the global and local scopes, respectively. These functions can be useful for debugging or for working with more complex programs.

4. What are lists and tuples? What is the key difference between lists and tuples?

Lists and tuples are two of the most commonly used data structures in Python. They both allow you to store multiple values in a single variable, but they have some important differences.

A list is a mutable sequence of elements that can be of different data types. Lists are defined using square brackets [], and the elements within the list are separated by commas. Lists can be modified by adding, removing or modifying elements. For example:

my_list = [1, 2, 3, "hello", True]

A tuple is an immutable sequence of elements that can also be of different data types. Tuples are defined using parentheses (), and the elements within the tuple are also separated by commas. Tuples cannot be modified once they are created. For example:

my_tuple = (1, 2, 3, "hello", True)

The main difference between lists and tuples is that lists are mutable, while tuples are immutable. This means that you can change the elements within a list after it has been created, but you cannot change the elements within a tuple. In general, if you need to store a collection of values that will not change, you should use a tuple. If you need to store a collection of values that may change, you should use a list.

5. What is Pep 8?

PEP 8 is a set of guidelines for coding in Python, created by Guido van Rossum, Barry Warsaw, and Nick Coghlan. It covers topics such as code layout, naming conventions, and programming practices to help developers write more readable and maintainable Python code.

Following PEP 8 guidelines can make your code more consistent and easier to understand, both for yourself and for other developers who may need to work with your code. Adhering to these guidelines can also help prevent common errors and make debugging easier.

Some of the key principles outlined in PEP 8 include using four spaces for indentation, limiting line length to 79 characters, using lowercase with underscores for variable and function names, and using uppercase for constants.

While following PEP 8 is not strictly required, it is considered to be a best practice in Python programming. Many Python projects, libraries, and frameworks have adopted PEP 8 as their coding standard, and many code editors and IDEs have built-in tools to help developers adhere to these guidelines.

6. What are the built-in data types in Python?

Python has several built-in data types, including integers, floating-point numbers, complex numbers, strings, lists, tuples, sets, and dictionaries. These data types are used to store and manipulate different types of data in Python.

• Integers are whole numbers, positive or negative.
• Floating-point numbers are numbers with decimal points.
• Complex numbers are numbers with a real and imaginary part.
• Strings are sequences of characters, enclosed in quotes.
• Lists are ordered collections of items, enclosed in square brackets.
• Tuples are ordered collections of items, enclosed in parentheses.
• Sets are unordered collections of unique items, enclosed in curly braces.
• Dictionaries are collections of key-value pairs, enclosed in curly braces with key-value pairs separated by colons.

7. How is the memory managed in Python?

Memory management in Python is handled by the Python Memory Manager. It is responsible for allocating and deallocating memory as necessary. Python uses a private heap space for storing objects, and has a garbage collector that automatically frees memory for objects that are no longer being used.

The Python Memory Manager uses a combination of reference counting and garbage collection to manage memory. Reference counting involves keeping track of the number of references to an object, and deallocating the object when the reference count reaches zero. Garbage collection involves identifying and freeing memory for objects that are no longer reachable.

Python also provides tools for managing memory manually, such as the gc module, which can be used to control the behavior of the garbage collector. Additionally, the sys module provides functions for getting information about memory usage and setting memory limits.

8. What are Python literals?

In Python, literals are values that are directly assigned to variables or used in expressions. This includes numeric literals (such as integers and floats), string literals, boolean literals (True and False), and more.

For example, if you write x = 5, 5 is a numeric literal that is being assigned to the variable x. Similarly, if you write y = "hello", "hello" is a string literal that is being assigned to the variable y.

Literals are important in Python because they provide a way to initialize variables with specific values without having to explicitly create an object or call a function. This makes it easier to write code quickly and concisely, especially for simple programs or scripts.

It’s worth noting that literals in Python are immutable, meaning that their values cannot be changed once they are created. For example, if you write x = 5 and then try to change the value of x to something else, you will get an error. However, you can still create new variables with new values using literals.

9. Explain about the Python Functions?

A function in Python is a block of reusable code that performs a specific task. In Python, functions are defined using the “def” keyword, followed by the function name, and a set of parentheses that may include parameters. The function body is indented and contains the code that performs the task.

Functions can return a value using the “return” keyword, and can be called by their name followed by parentheses, optionally passing arguments. Python also supports anonymous functions, called “lambda” functions, which are defined using the “lambda” keyword and have a concise syntax.

Functions are an important concept in Python programming as they provide a way to modularize code, making it more readable, maintainable, and reusable. By breaking down complex tasks into smaller, more manageable functions, developers can write code that is easier to debug and test, and that can be used in a variety of different programs and applications.

Python has several built-in functions that are commonly used, such as print(), len(), and range(). In addition, Python also allows developers to define their own functions, providing flexibility and customization.

10. What is the zip() function in Python?

The zip() function in Python is used to “zip” or combine two or more lists into a single iterable object, which can then be looped over or converted into a list.

For example, if we have two lists, list1 and list2, we can use the zip() function to create a new list that contains tuples with corresponding elements from both lists. Here’s an example:

list1 = [1, 2, 3]
list2 = ['a', 'b', 'c']
result = zip(list1, list2)
print(list(result))

Output:

[(1, 'a'), (2, 'b'), (3, 'c')]

In this example, the zip() function combines list1 and list2 into a single iterable object, which is then converted into a list using the list() function. Each tuple in the resulting list contains the corresponding elements from both lists.

The zip() function can also be used with more than two lists. If the lists are of different lengths, the resulting iterable will only contain tuples up to the length of the shortest list.

11. What are modules and packages in Python?

In Python, a module is a file containing Python definitions and statements. A package is a collection of modules. A package can have sub-packages, which themselves can contain modules or even other sub-packages. Both modules and packages help organize code in a structured and reusable way.

Modules are used to group related functions, classes, and variables together into a single file, making it easier to manage and maintain code. Modules can be imported into other Python scripts using the “import” statement, allowing developers to reuse code across multiple files and projects.

Packages are used to group related modules together into a single namespace, making it easier to organize and manage larger projects. Packages can be nested, allowing for even greater organization and flexibility.

Python has a large and active community of developers who have created a wide range of modules and packages that extend the capabilities of Python. Some popular examples include NumPy for numerical computing, Pandas for data analysis, and Flask for web development.

12. What are global, protected and private attributes in Python?

In Python, there is no strict concept of access modifiers like public, protected or private, as in some other programming languages such as Java. However, Python does have some conventions that can be used to indicate the level of accessibility of attributes.

Global attributes are those that are defined at the module level and can be accessed from anywhere in the code. These attributes are typically used to store data or functions that need to be shared across multiple parts of a program.

Protected attributes are those that are prefixed with a single underscore (_) in their name. This convention indicates that the attribute should not be accessed directly from outside the class or module where it is defined, but can be accessed from within the class or module or its subclasses. However, this is just a convention and it is still possible to access protected attributes from outside the class or module.

Private attributes are those that are prefixed with two underscores (__). This convention indicates that the attribute should not be accessed directly from anywhere outside the class where it is defined. Python uses name mangling to change the name of the attribute to include the class name, making it harder to access from outside the class. For example, an attribute named __value in a class named MyClass would be accessed as _MyClass__value from outside the class.

13. What is Python’s parameter passing mechanism?

Python uses a mechanism called “pass by object reference“. This means that when a function is called, the arguments are passed as references to objects. The references are then used to access the actual objects. This allows for efficient memory usage and the ability to modify mutable objects in place.

In simple word, when a function is called with an argument in Python, the reference to the object is passed to the function. This means that the function can access and modify the object that the reference points to.

However, it’s important to note that immutable objects, such as numbers and strings, cannot be modified in place. Instead, a new object must be created.

14. How to overload constructors or methods in Python?

In Python, you can overload constructors or methods by defining multiple methods or constructors with the same name, but different parameters. When you call the method or constructor, Python will choose the correct one to execute based on the number and types of arguments passed in.

For example, let’s say you have a class called Person with a constructor that takes in a name and an age:

class Person:
    def init(self, name, age):
        self.name = name
        self.age = age

If you want to create a second constructor that only takes in a name and sets the age to 0 by default, you can do this:

class Person:
    def init(self, name, age):
    self.name = name
    self.age = age
    def __init__(self, name):
        self.name = name
        self.age = 0

Now you can create a Person object with either one or two arguments:

p1 = Person('Alice', 25) # creates a person with name 'Alice' and age 25
p2 = Person('Bob') # creates a person with name 'Bob' and age 0

It’s important to note that you cannot overload methods or constructors based solely on their return type. In Python, the return type of a method is not part of its signature, so you cannot have two methods with the same name and parameters but different return types.

15. What is the difference between remove() function and del statement?

n Python, remove() is a function that removes the first occurrence of a specified element from a list, whereas del is a statement that can be used to delete an item from a list or a variable from memory. The remove() function raises a ValueError if the specified element is not found in the list, while del raises a NameError if the variable being deleted is not defined.

So, the main difference between remove() function and del statement is that remove() removes the element based on its value while del removes the element based on its index. For example:

Using remove() function

my_list = [1, 2, 3, 4, 5]
my_list.remove(3)
print(my_list) # Output: [1, 2, 4, 5]

Using del statement

my_list = [1, 2, 3, 4, 5]
del my_list[2]
print(my_list) # Output: [1, 2, 4, 5]

In the first example, remove() is used to remove the value 3 from the list my_list. In the second example, del is used to remove the element at index 2 (i.e., the third element) from the list my_list.

It is important to note that remove() only removes the first occurrence of the specified element in the list. If there are multiple occurrences of the element, only the first one is removed. If you want to remove all occurrences of the element, you can use a loop or list comprehension.

16. What is init?

The init is a method in Python classes that is called when an instance of the class is created. It is used to define the properties and behaviors of the instance, and can take arguments to initialize those properties.

For example, if you have a class called Car, you could define the __init__ method to take arguments for the make, model, and year of the car, and use those arguments to initialize the corresponding properties of the instance:

class Car:
    def init(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year

Now, when you create an instance of the Car class, you can pass in the make, model, and year as arguments, and those values will be used to initialize the properties of the instance:

mycar = Car('Toyota', 'Corolla', 2021)
print(mycar.make) # Output: Toyota
print(mycar.model) # Output: Corolla
print(mycar.year) # Output: 2021

In this example, the __init__ method takes three arguments (make, model, and year) and assigns them to the corresponding properties (self.make, self.model, and self.year) of the instance.

17. What is break, continue and pass in Python?

In Python, break, continue and pass are control statements used to change the flow of a loop or a conditional statement.

• break is used to terminate a loop prematurely and move onto the next statement after the loop.
• continue is used to skip to the next iteration of the loop, without executing the remaining statements in the current iteration.
• pass is used as a placeholder statement when no action is required, as Python does not allow empty code blocks.

For instance, consider the following example where we want to print the numbers from 0 to 9, but skip the number 5:

for i in range(10):
    if i == 5:
        continue
    print(i)

In this example, the continue statement causes the loop to skip printing the number 5, and move on to the next iteration to print the remaining numbers.

On the other hand, the break statement can be used to terminate a loop early, as shown in the following example:

for i in range(10):
    if i == 5:
        break
    print(i)

In this example, the break statement causes the loop to terminate after printing the numbers 0 to 4, and move on to the next statement after the loop.

Finally, the pass statement is used as a placeholder when no action is required, as shown in the following example:

for i in range(10):
    if i == 5:
        pass
    else:
        print(i)

In this example, the pass statement does not do anything, and the loop continues to execute the remaining statements in the current iteration. However, it is included to indicate that no action is required in case the condition is met.

18. What are unit tests in Python?

Unit tests in Python are automated tests that verify the functionality of individual parts, or units, of a codebase. They are typically written by developers and are designed to ensure that each piece of code works as expected in isolation from the rest of the system. This allows developers to catch and fix bugs early in the development process.

Unit tests in Python are an important part of the software development process. They can help ensure that the behavior of a function or class is consistent over time and across different environments, and can also help prevent regressions when changes are made to the codebase.

To write unit tests in Python, developers typically use a testing framework such as unittest or pytest. These frameworks provide a set of tools and conventions for writing and running tests, including assertions to check the output of functions and fixtures to set up test data.

Good unit tests should be fast, reliable, and repeatable. They should also be isolated from other parts of the system, meaning that they should not depend on external resources such as databases or network services. This helps ensure that failures in one part of the system do not affect other parts of the system.

19. What is docstring in Python?

A docstring in Python is a string literal that is used to document a module, class, function, or method. It is the first line after the definition and it is enclosed in triple quotes.

Docstrings are used to provide information about the purpose and usage of the code. They are also used to provide information about the parameters, return values, and any exceptions that may be raised.

Docstrings can be accessed using the __doc__ attribute of an object. For example, if you define a function my_function with a docstring, you can access the docstring using my_function.__doc__.

It’s important to include docstrings in your code, as they help other developers understand how to use your code and can make it easier to maintain and debug. In addition, well-written docstrings can also be used to generate documentation automatically, using tools such as Sphinx.

20. What are local variables and global variables in Python?

In Python, local variables are variables that are defined within a function and can only be accessed within that function. Global variables, on the other hand, are variables that are defined outside of any function and can be accessed by any part of the program.

The use of global variables should be minimized in favor of local variables, as global variables can lead to unexpected behavior and make it harder to understand and debug code. It’s generally a good practice to use local variables within functions, and to pass any necessary values as arguments to the function.

For example, consider the following code:

x = 10 # global variable
def my_function():
    y = 5 # local variable
    print(x + y) # prints 15 
my_function()

In this example, x is a global variable that can be accessed from within the function my_function. However, y is a local variable that can only be accessed within the function.

It’s important to note that if a local variable has the same name as a global variable, the local variable will take precedence within the function. For example:

x = 10 # global variable

def my_function():
    x = 5 # local variable
    print(x) # prints 5
my_function()
print(x) # prints 10

In this example, the local variable x within the function takes precedence over the global variable x. When my_function is called, it prints the value of the local variable x (i.e., 5). However, when the function is finished and x is printed again outside of the function, it prints the value of the global variable x (i.e., 10).

21. What is type conversion in Python?

Type conversion in Python is the process of changing the data type of a variable or a value from one type to another. For example, converting an integer to a string or a string to a float.

Python provides built-in functions to perform type conversion, such as int(), float(), str(), list(), tuple(), set(), and dict(). These functions take a value or a variable and convert it to a new type.

For example, to convert a string to an integer, you can use the int() function:

string_num = '10'
int_num = int(string_num)
print(int_num)

This will output:

10

Similarly, to convert an integer to a string, you can use the str() function:

int_num = 10
string_num = str(int_num)
print(string_num)

This will output:

'10'

Type conversion is useful when working with different data types and performing operations on them. However, it’s important to be aware of potential errors or loss of information that can occur when converting between certain types of data. For example, converting a float to an integer can result in the loss of decimal places.

22. Is indentation required in Python?

Yes, indentation is required in Python. It is used to define the block of code for statements such as if/else statements, loops, and functions.

Indentation is used instead of curly braces or keywords like “begin” and “end” in other programming languages. It is important to maintain consistent indentation throughout your code to avoid syntax errors.

For example, consider the following code:

if x > 5:
    print("x is greater than 5")

This code will result in a syntax error because the print statement is not indented properly. To fix this, we need to indent the print statement:

if x > 5:
     print("x is greater than 5")

Now the code will execute correctly.

23. What is the difference between an array and a list in Python?

Here is a table comparing Python arrays and lists:

24. What is PYTHONPATH?

PYTHONPATH is an environment variable in Python that tells the interpreter where to locate the module files imported into a program. It should include the Python source library directory and the directories containing Python source code.

This is particularly useful when working with multiple Python projects or when using third-party packages that are not installed in the default Python environment.

By setting the PYTHONPATH variable, you can ensure that the interpreter can find the necessary modules and packages, even if they are not located in the standard Python library directories.

To set the PYTHONPATH variable, you can use the following command in the terminal or command prompt:

export PYTHONPATH=/path/to/directory

or

set PYTHONPATH=/path/to/directory

Replace /path/to/directory with the path to the directory containing your Python source code.

25. What are namespaces?

Python namespaces are containers for storing variables, functions, and other objects. They provide a way to separate and organize different parts of a program to avoid naming conflicts and to make the code more readable and maintainable.

There are three types of namespaces in Python:

• Local namespace: This namespace contains local variables and is created when a function is called. It is destroyed when the function returns.
• Global namespace: This namespace contains global variables and is created when the program starts. It is destroyed when the program ends.
• Built-in namespace: This namespace contains built-in functions and modules that are available to all Python programs. It is automatically created when the program starts and cannot be destroyed.

Python searches for a variable in the local namespace first, then in the global namespace, and finally in the built-in namespace. If the variable is not found in any of these namespaces, a NameError is raised.

26. What is slicing in Python?

Slicing in Python refers to extracting a specific section or subset of elements from a sequence object, such as a list or a string. It involves specifying a start and end index, and an optional step value, within square brackets following the sequence object.

For example, consider the following list:

my_list = [1, 2, 3, 4, 5]

To slice this list to get only the elements from index 1 to 3 (inclusive), we can use the following code:

sliced_list = my_list[1:4]
print(sliced_list)

This will output:

[2, 3, 4]

In this example, we specified the start index as 1 and the end index as 4 (exclusive), which resulted in a new list containing the elements from index 1 to 3 of the original list.

We can also specify a step value, which determines the increment between each index in the slice. For example:

my_string = "Hello, world!"
sliced_string = my_string[::2]
print(sliced_string)

This will output:

Hlo ol!

In this example, we specified a step value of 2, which resulted in a new string containing every second character of the original string.

Slicing is a powerful feature of Python that allows us to work with specific subsets of data within a sequence object, without modifying the original object. It is commonly used in data manipulation and analysis tasks, as well as in general programming tasks involving lists and strings.

27. What is swapcase() function in Python?

In Python, swapcase() is a built-in function that returns a copy of a string with all its uppercase letters converted to lowercase and vice versa.

For example, if we have the following string:

my_string = "HeLLo WoRLd"

We can use the swapcase() function to convert all uppercase letters to lowercase and all lowercase letters to uppercase:

new_string = my_string.swapcase()
print(new_string) # hEllO wOrlD

This function is useful when we need to manipulate strings and change the case of its characters. It can be used in various scenarios, such as formatting text or processing user input.

28. What is scope resolution in Python?

In Python, scope resolution refers to the process of determining the value of a variable within a program. When a variable is used in Python, the interpreter first looks for the variable within the current scope (such as a function or class), and if it’s not found, it then looks for the variable in the parent scopes until it reaches the global scope. If the variable is still not found, a NameError is raised.

This means that if a variable is defined within a function, it is only accessible within that function (i.e., within its local scope), and cannot be accessed outside of the function or in other functions. Similarly, if a variable is defined outside of any function, it is considered a global variable and can be accessed from anywhere in the program.

29. What are decorators in Python?

Decorators in Python are a way to modify or enhance the behavior of a callable object (functions, methods, or classes) without changing its source code. They allow you to wrap one function with another function and modify its behavior in a non-intrusive way.

To define a decorator, you simply define a new function that takes in a function as an argument, modifies it in some way, and returns the modified function. You can then apply the decorator to any function by placing the decorator name (@decorator_name) above the function definition.

For example, consider the following decorator that prints the time taken to execute a function:

import time
def time_it(func):
    def wrapper(*args, *kwargs): start_time = time.time() result = func(args, **kwargs)
        end_time = time.time()
        print(f"Time taken to execute {func.name}: {end_time - start_time}")
return result
return wrapper

@time_it
def my_function():
# function code here
pass

In this example, the time_it function is a decorator that takes in a function as an argument and returns a new function wrapper that wraps the original function. The wrapper function uses the time module to measure the time taken to execute the original function, prints the result, and returns the original function’s result.

The @time_it decorator is then applied to the my_function function, which means that whenever my_function is called, it will be wrapped by the time_it decorator and the time taken to execute the function will be printed.

30. What are dict and list comprehensions?

Dict and List comprehensions are features in Python that allow for the concise creation of dictionaries and lists. They use a compact syntax to generate a new dictionary or list based on an iterable object, with optional conditions to filter the results.

List comprehensions are used to create new lists by iterating over an existing iterable object, such as a list or a string. They have a basic structure of [expression for variable in iterable if condition].

For example, to create a new list of the squares of the numbers from 1 to 10, you can use the following list comprehension:

squares = [x**2 for x in range(1, 11)]
print(squares)

This will output:

[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

In this example, we used a list comprehension to iterate over the range of numbers from 1 to 10, and used the expression x**2 to generate a new list of the squares of these numbers.

Dict comprehensions, on the other hand, are used to create new dictionaries by iterating over an existing iterable object and generating key-value pairs based on the iteration. They have a basic structure of {key_expression: value_expression for variable in iterable if condition}.

For example, to create a new dictionary with the squares of the numbers from 1 to 5 as keys and the corresponding factorials as values, you can use the following dict comprehension:

import math
squares_and_factorials = {x**2: math.factorial(x) for x in range(1, 6)}
print(squares_and_factorials)

This will output:

{1: 1, 4: 2, 9: 6, 16: 24, 25: 120}

In this example, we used a dict comprehension to iterate over the range of numbers from 1 to 5, and used the expressions x**2 and math.factorial(x) to generate key-value pairs for the new dictionary.

31. What are pickling and unpickling?

Pickling and unpickling are two operations that allow you to convert a Python object (e.g. a list or dictionary) into a string representation (serialization) and vice versa (deserialization). Pickling is the process of converting a Python object hierarchy into a byte stream, while unpickling is the reverse operation.

Pickling is useful when you want to store or transmit data over a network, and you need to convert the data into a format that can be easily transmitted or stored. For example, you may want to save the state of a program to a file, or send data between different processes on a network.

To pickle an object, you can use the pickle module in Python. Here’s an example:

import pickle
create an object to pickle
my_object = {'name': 'John', 'age': 30, 'occupation': 'programmer'}
pickle the object
with open('my_pickle_file.pkl', 'wb') as f:
pickle.dump(my_object, f)

In this example, we create a dictionary object my_object, and then use the pickle.dump() function to pickle the object and save it to a file called my_pickle_file.pkl. The wb argument specifies that the file should be opened in binary mode for writing.

To unpickle an object, you can use the pickle.load() function. Here’s an example:

import pickle
unpickle the object
with open('my_pickle_file.pkl', 'rb') as f:
my_object = pickle.load(f)
print the unpickled object
print(my_object)

In this example, we use the pickle.load() function to unpickle the object from the file my_pickle_file.pkl, and then print the unpickled object to the console.

32. What are generators in Python?

Generators are a type of iterable, like lists or tuples, but unlike those objects, they don’t store all of their values in memory at once. Instead, they generate each value on-the-fly as they are iterated over using the “yield” keyword. This can be more memory-efficient than creating an entire list or tuple when the full sequence of values isn’t needed right away.

Generators are defined using a function that contains one or more yield statements. When the function is called, it returns a generator object that can be iterated over using a for loop, just like a list or tuple.

For example, here’s a simple generator function that produces the Fibonacci sequence:

def fibonacci():
a, b = 0, 1
while True:
yield b
a, b = b, a + b

When this function is called, it returns a generator object that can be used to generate the Fibonacci sequence on-the-fly:

fib = fibonacci()
next(fib)
1
next(fib)
1
next(fib)
2
next(fib)
3
next(fib)
5

Note that we can use the next() function to generate the next value in the sequence. We can also use a for loop to generate the entire sequence:

for i in fibonacci():
… if i > 100:
… break
… print(i)
1
1
2
3
5
8
13
21
34
55
89

33. What is the difference between xrange and range in Python?

The main difference between xrange and range in Python is that range returns a list object containing the specified range of values, while xrange returns a generator object that can be used to iterate over the range of values.

Here are some differences between xrange and range in Python presented in a table format:

34. How are arguments passed by value or by reference in python?

In Python, arguments are passed by assignment. When a function is called, the values of the arguments are assigned to the parameter names in the function definition. If an argument is a mutable object (such as a list or dictionary) and the function modifies the object, the changes will be visible to the caller. If the argument is an immutable object (such as a number, string, or tuple), the function cannot modify the object, as it is passed by value.

Regarding the question “How are arguments passed by value or by reference in python?”, Python does not have the concept of passing arguments by reference or by value, as in some other programming languages. Instead, everything in Python is an object and variables are references to objects.

When an object is passed as an argument to a function, a copy of the reference to the object is created and passed to the function. This means that the function can modify the object, but it cannot change the reference to the object outside of the function.

In other words, in Python, everything is passed by reference, but the reference itself is passed by value. This can lead to some confusion, but it also allows for more flexibility and efficiency in programming.

35. Explain split() and join() functions in Python?

The split() function in Python is a method that allows you to split a string into a list of substrings, based on a specified separator. The join() function, on the other hand, is a method that concatenates a list of strings into a single string, using a specified delimiter between each element.

For example, if we have the following string:

my_string = "Hello, world!"

We can use the split() function to split the string into a list of substrings based on the comma separator:

split_string = my_string.split(",")
print(split_string)

This will output:

['Hello', ' world!']

In this example, we used the comma “,” separator to split the string into two substrings “Hello” and ” world!”. The resulting substrings are stored in a list.

We can also use the join() function to concatenate a list of strings into a single string using a specified delimiter. For example:

my_list = ['Hello', 'world!']
joined_string = ", ".join(my_list)
print(joined_string)

This will output:

'Hello, world!'

In this example, we used the comma and space delimiter “, ” to concatenate the list of strings into a single string “Hello, world!”.

Both split() and join() functions are commonly used in Python for manipulating strings and lists. They are especially useful when dealing with large datasets or when performing text processing tasks.

36. What is the use of help() and dir() functions?

The help() function in Python is used to get documentation about a specific module, function, class, or method in Python. It displays a description of the object, the parameters it takes, and the return value.

The dir() function is used to get a list of all the attributes and methods of an object in Python. It returns a list of the names of the attributes and methods of the object, which can be useful when exploring unfamiliar objects or modules.

Regarding the help() function, it is a built-in function in Python, which means it is always available to use. To use it, you simply pass the object you want to get help for as an argument. For example, to get help for the math module in Python, you can use the following command:

help(math)

This will display a detailed documentation about the math module, including all its functions, constants, and classes.

Regarding the dir() function, it is also a built-in function in Python that returns a list of all the attributes and methods of an object. To use it, you simply pass the object you want to explore as an argument. For example, to get a list of all the attributes and methods of the math module, you can use the following command:

dir(math)

This will return a list of all the attributes and methods of the math module. You can use this list to explore the module and learn more about its functions and classes.

37. What is the difference between .py and .pyc files?

Here is a table showing the differences between .py and .pyc files:

38. What does [::-1} do?

In Python, [::-1] is a slicing syntax used to reverse the order of elements in a sequence like a list, tuple, or string. It returns a new sequence with the elements in the opposite order.

For example, if we have a string “hello” and we apply the [::-1] slicing, it will return the string “olleh” which is the reverse of the original string.

Here’s an example:

my_string = "hello"
reversed_string = my_string[::-1]
print(reversed_string)

This will output:

olleh

This slicing syntax can be useful when we need to reverse the order of elements in a sequence or when we need to iterate through a sequence in reverse order.

39. Is it possible to call a parent class without its instance creation?

No, it is not possible to call a parent class without creating an instance of it. In object-oriented programming, a class is a blueprint for creating objects, and calling a parent class typically involves creating a subclass that inherits from the parent class and calls its methods or attributes.

Some built-in functions in Python can be used to interact with parent classes, such as super(). The super() function allows you to call a method from a parent class in a subclass, without explicitly naming the parent class.

40. What are negative indexes and why are they used?

Negative indexes refer to the ability to access elements in a sequence by counting from the end of the sequence, rather than from the beginning. For example, in a list of length n, the index -1 refers to the last element, -2 refers to the second-to-last element, and so on. Negative indexes are useful in situations where the length of the sequence is unknown or variable, or when accessing elements from the end of a sequence is more natural or efficient.

Negative indexes can be used with many different types of sequences in Python, including lists, tuples, and strings. They are often used in combination with slicing syntax to extract sub-sequences from a larger sequence. For example, the slicing syntax my_list[-3:] will return the last three elements of a list, regardless of the length of the list.

It is important to note that not all sequences in Python support negative indexing. For example, sets and dictionaries use hash tables to store their elements, and the order of the elements is not guaranteed. Therefore, negative indexing is not applicable to these data structures.

Python Interview Questions for Experienced

The following question test the python knowledge in depth.

41. How to create an empty class in python?

An empty class can be created in Python by using the pass keyword as the body of the class. For example:

class MyEmptyClass:
    pass

This creates a class called MyEmptyClass that doesn’t have any properties or methods defined within it. The pass keyword is a placeholder statement that does nothing, but it allows the class to be defined without any errors.

Creating an empty class can be helpful in situations where we want to define a class that will be inherited by other classes, but we don’t want to define any properties or methods in the base class. It can also be used as a placeholder for a class that will be implemented later on.

42. Difference between new and override modifiers in Python?

Modifiers are special keywords in Python that can be used to modify the behavior of classes, methods, and functions. There are several modifiers available in Python, including new and override modifiers.

• New modifier: The new modifier is used to define a new method or attribute in a subclass that has the same name as a method or attribute in its superclass. This is also known as method overloading. The new method or attribute in the subclass will override the method or attribute in the superclass.
• Override modifier: The override modifier is used to override a method or attribute in a subclass that has the same name as a method or attribute in its superclass. This is also known as method overriding. The overridden method or attribute in the subclass will replace the method or attribute in the superclass.

Here are some differences between new and override modifiers in Python:

43. Why is finalize used?

“finalize” is often used in programming to refer to a method or process that is called at the end of an object’s life cycle, typically for cleanup or releasing resources. It allows developers to ensure that the object is properly disposed of and any necessary cleanup is performed before it is removed from memory.

In Python specifically, the __del__() method is used for finalization. It is a special method that is automatically called when an object is about to be destroyed. The __del__() method can be used to perform any necessary cleanup, such as closing files or releasing locks.

However, it is important to note that the __del__() method does not guarantee that finalization will always occur. In some cases, such as when the Python interpreter is shutting down or when circular references are involved, the __del__() method may not be called. Therefore, it is generally recommended to use other mechanisms, such as the with statement or the finally block, to ensure proper finalization and resource release.

44. What is the __init__ method in python?

In Python, the __init__ method is a special method that is called when an object is created. It is used to initialize the object’s attributes or perform any other setup that is required for the object to function properly.

The __init__ method is defined within a class and takes at least one argument, which is typically named self. The self argument refers to the object being created, and is used to access its attributes and methods.

Here’s an example of how the __init__ method can be used to initialize the attributes of a class:

class MyClass:
    def init(self, name, age):
        self.name = name
        self.age = age

person1 = MyClass("John", 25)
person2 = MyClass("Jane", 30)

print(person1.name) # Output: John
print(person2.age) # Output: 30

In this example, we define a class MyClass with an __init__ method that takes two arguments – name and age. The self argument is automatically passed in when an object of the class is created.

We then create two objects of the MyClass class – person1 and person2 – and pass in the required arguments to initialize their name and age attributes. Finally, we print out the values of the name and age attributes for each object.

The __init__ method is a powerful tool in Python that allows us to create objects with customized attributes and behavior. By properly initializing the attributes of an object, we can ensure that it behaves correctly and efficiently in our program.

45. How will you check if a class is a child of another class?

To check if a class is a child of another class in Python, you can use the built-in function issubclass(). The syntax is issubclass(childClass, parentClass), and it returns True if childClass is a subclass of parentClass, and False otherwise.

Here’s an example:

class Animal:
    pass
class Dog(Animal):
    pass
class GoldenRetriever(Dog):
    pass
print(issubclass(Dog, Animal)) # Output: True
print(issubclass(GoldenRetriever, Animal)) # Output: True
print(issubclass(GoldenRetriever, Dog)) # Output: True

In this example, we define three classes – Animal, Dog, and GoldenRetriever. The Dog class is a subclass of Animal, and GoldenRetriever is a subclass of Dog.

We then use the issubclass() function to check if Dog is a subclass of Animal, if GoldenRetriever is a subclass of Animal, and if GoldenRetriever is a subclass of Dog. In all cases, the function returns True, indicating that the classes are indeed subclasses of the specified parent classes.

Using issubclass() is a simple and effective way to check if a class is a child of another class in Python. It can be useful in many situations, such as when designing class hierarchies or when working with third-party libraries that define complex class structures.

46. How to combine different Pandas dataframes?

You can combine different pandas dataframes using functions like concat(), merge(), or join(). concat() stacks dataframes on top of each other or side by side, merge() combines dataframes based on common columns or indices, and join() combines dataframes based on their indices. The method you choose will depend on the specific needs of your data.

For example, if you have two dataframes df1 and df2 with the same columns, you can concatenate them vertically using pd.concat([df1, df2]). If you want to concatenate them horizontally, you can use pd.concat([df1, df2], axis=1).

Similarly, if you have two dataframes with common columns, you can merge them using pd.merge(df1, df2, on='common_column'). If the column names are different, you can use left_on and right_on parameters to specify the common columns.

Lastly, if you have two dataframes with common indices, you can join them using df1.join(df2). You can also specify the join type using the how parameter.

47. Can you get items of series A that are not available in another series B?

To solve this question, one possible solution is to use the isin() method in Pandas. This method can be used to check if each element in a Series is contained in another Series. By using the negation operator ~, we can invert the result to get the items that are not in the other Series.

Here’s an example:

import pandas as pd
series_a = pd.Series([1, 2, 3, 4, 5])
series_b = pd.Series([3, 4, 5, 6, 7])
result = series_a[~series_a.isin(series_b)]
print(result)

In this example, we create two Series series_a and series_b, and then use the isin() method to check which elements in series_a are also present in series_b. By using the negation operator ~, we invert the result to get the elements that are not present in series_b.

The output of this program will be:

0    1
1    2
dtype: int64

This shows that items 1 and 2 in series_a are not present in series_b.

48. How to items that are not common to both the given series A and B?

The items that are not common to both series A and B can be obtained by performing a set operation called “Symmetric Difference” or “Disjunctive Union”. This operation can be performed using set theory or by using programming languages like Python, which have a built-in function for finding the symmetric difference of two sets.

In Python, we can use the set() function to convert the two series into sets and then use the “^” operator to find the symmetric difference. Here’s an example:

import pandas as pd
series_a = pd.Series([1, 2, 3, 4, 5])
series_b = pd.Series([3, 4, 5, 6, 7])
result = set(series_a) ^ set(series_b)
print(result)

In this example, we create two Series series_a and series_b, and then convert them into sets using the set() function. We then use the “^” operator to find the symmetric difference of the two sets, which gives us the items that are not common to both series.

The output of this program will be:

{1, 2, 6, 7}

This shows that the items 1 and 2 are in series A but not in series B, and the items 6 and 7 are in series B but not in series A.

49. While importing data from different sources, can the Pandas library recognize dates?

Yes, the pandas library can recognize dates while importing data from different sources. It has built-in functions to parse and convert date strings into datetime objects. This makes it easier to work with time-series data and perform operations like filtering, grouping, and resampling based on date and time. Some of the built-in functions in pandas to parse date strings include to_datetime(), date_range(), and read_csv().

• The to_datetime() function can be used to convert a string or a list of strings into a datetime object. It can handle various date and time formats, and can also handle missing or ambiguous values.
• The date_range() function can be used to generate a sequence of dates at a specified frequency. This can be useful for creating a time index for a pandas DataFrame or Series.
• The read_csv() function can be used to read a CSV file containing date and time information and parse it into a pandas DataFrame with datetime index.

50. Does python support multiple inheritance?

Yes, Python supports multiple inheritance, which means a class can inherit from multiple base classes. However, it is important to use it carefully to avoid issues like the diamond problem.

Multiple inheritance in Python allows a subclass to inherit from multiple parent classes. This can be useful in situations where a subclass needs to combine the behavior of multiple parent classes. However, it can also lead to complexity and ambiguity if not used carefully.

One common issue that can arise with multiple inheritance is the diamond problem. This occurs when two parent classes of a subclass have a common base class, and the subclass tries to access a method or attribute of the common base class. In this situation, it may not be clear which implementation of the method or attribute should be used, leading to ambiguity and potential bugs.

To avoid the diamond problem and other issues with multiple inheritance, it is important to use it carefully and thoughtfully. In general, it is recommended to favor composition over inheritance, and to use multiple inheritance only when necessary and when it can simplify the design of the code.

Here’s an example code:

class Parent1:
    def method1(self):
        print("Method 1 from Parent 1")
        
class Parent2:
    def method2(self):
        print("Method 2 from Parent 2")

class Child(Parent1, Parent2):
    def method3(self):
        print("Method 3 from Child")

# create object of Child class
obj = Child()

# calling methods
obj.method1() # Output: Method 1 from Parent 1
obj.method2() # Output: Method 2 from Parent 2
obj.method3() # Output: Method 3 from Child

In this example, the Child class is inheriting from both Parent1 and Parent2 classes. The Child class can access the methods and attributes of both parent classes.

51. What is Polymorphism in Python?

Polymorphism is a concept in object-oriented programming where objects of different classes can be treated as if they are objects of the same class. In Python, this is achieved through method overriding and method overloading.

Method overriding allows a subclass to provide a different implementation of a method that is already defined in its parent class. This can be useful when the subclass needs to extend or modify the behavior of the inherited method.

Method overloading, on the other hand, allows a class to define multiple methods with the same name but different parameters. This allows the same method name to be used for different purposes, depending on the types and number of arguments passed in.

Polymorphism is a powerful concept that allows for the more flexible and modular code design. By designing classes and methods that can be used interchangeably, we can create code that is more extensible and easier to maintain.

Here’s an example code to demonstrate polymorphism in Python:

class Animal:
    def speak(self):
        pass

class Dog(Animal):
    def speak(self):
        return "Woof!"

class Cat(Animal):
    def speak(self):
        return "Meow!"

def animal_speak(animal):
    print(animal.speak())

# create objects of Dog and Cat classes
dog = Dog()
cat = Cat()

# call the animal_speak method with Dog and Cat objects
animal_speak(dog) # Output: Woof!
animal_speak(cat) # Output: Meow!

In this example, we have a base class Animal and two subclasses Dog and Cat. The Animal class has a method speak, which is overridden in the Dog and Cat subclasses.

The animal_speak function takes an object of the Animal class and calls the speak method. When we pass the dog object, it calls the speak method of the Dog class and returns “Woof!”. Similarly, when we pass the cat object, it calls the speak method of the Cat class and returns “Meow!”.

52. Define encapsulation in Python?

Encapsulation is a fundamental concept in object-oriented programming that refers to the practice of keeping the implementation details of a class hidden from the outside world and accessing them only through a public interface. In Python, encapsulation is achieved through the use of private attributes and methods, which are denoted by a double underscore prefix before their name.

Private attributes and methods can only be accessed within the class that defines them, and not from outside the class. This helps to prevent accidental modification of internal data, and ensures that the class can maintain its invariants and correct behavior.

In addition to private attributes and methods, Python also provides protected attributes and methods, which are denoted by a single underscore prefix before their name. Protected attributes and methods can be accessed by subclasses and other classes within the same module, but not from outside the module.

Encapsulation is an important concept in software development, as it helps to improve code maintainability, reusability, and reliability. By hiding implementation details, encapsulation allows classes to be modified and improved without affecting the rest of the codebase, and helps to prevent unintended side effects and bugs.

Here’s an example code to demonstrate encapsulation in Python:

class Student:
    def __init__(self, name, roll_no, branch):
        self.__name = name
        self._roll_no = roll_no
        self.branch = branch
        
    def display_details(self):
        print("Name:", self.__name)
        print("Roll No:", self._roll_no)
        print("Branch:", self.branch)

# create object of Student class
student = Student("John", 101, "CSE")

# try to access private member
print(student.__name) # Error: 'Student' object has no attribute '__name'

# try to access protected member
print(student._roll_no) # Output: 101

# access public member
student.display_details() # Output: Name: John, Roll No: 101, Branch: CSE

In this example, we have a Student class that has three attributes – __name (private), _roll_no (protected), and branch (public). The __init__ method initializes these attributes with the values passed as arguments. The display_details method is a public method that displays the values of all the attributes. We can access the public method and protected member directly from the object of the Student class. However, we cannot access the private member directly, and it raises an error.

53. How do you do data abstraction in Python?

Data abstraction in Python can be achieved through the use of classes and objects. By defining a class with attributes and methods, you can encapsulate data and functionality into a single unit, and expose only the relevant information to the user. This allows for a higher level of abstraction, as the user does not need to know the underlying implementation details.

For example, let’s say you want to create a program that simulates a bank account. You could define a class called BankAccount with attributes like account_number, balance, and owner_name, and methods like deposit(), withdraw(), and get_balance(). By encapsulating the data and functionality of the bank account into a class, you can create multiple instances of the class (i.e., multiple bank accounts) without having to write duplicate code.

Another benefit of data abstraction is that it allows for better code organization and modularity. By separating the implementation details of a class from the rest of the program, you can create a more modular and scalable codebase that is easier to maintain and extend.

Here’s an example code to demonstrate data abstraction in Python:

from abc import ABC, abstractmethod

class Shape(ABC):
    @abstractmethod
    def area(self):
        pass

    @abstractmethod
    def perimeter(self):
        pass

class Rectangle(Shape):
    def __init__(self, length, breadth):
        self.length = length
        self.breadth = breadth

    def area(self):
        return self.length * self.breadth

    def perimeter(self):
        return 2 * (self.length + self.breadth)

class Circle(Shape):
    def __init__(self, radius):
        self.radius = radius

    def area(self):
        return 3.14 * self.radius ** 2

    def perimeter(self):
        return 2 * 3.14 * self.radius

# create objects of Rectangle and Circle classes
rect = Rectangle(5, 10)
circle = Circle(7)

# call the area and perimeter methods
print("Area of Rectangle:", rect.area()) # Output: 50
print("Perimeter of Rectangle:", rect.perimeter()) # Output: 30
print("Area of Circle:", circle.area()) # Output: 153.86
print("Perimeter of Circle:", circle.perimeter()) # Output: 43.96

In this example, we have an abstract class Shape that has two abstract methods area and perimeter. The Rectangle and Circle classes are subclasses of the Shape class and implement these methods. We can create objects of these classes and call their methods without knowing the implementation details. The implementation of the methods is hidden from the outside world, and only the essential features (area and perimeter) are exposed.

54. Does python make use of access specifiers?

Python does not have traditional access specifiers like other object-oriented languages. However, it uses naming conventions to indicate the intended visibility of a method or attribute.

• A single underscore prefix indicates that a method or attribute is intended to be protected.
• A double underscore prefix indicates that it is intended to be private.

These naming conventions are not enforced by the language itself, but are generally followed by Python developers to indicate the intended usage of a method or attribute. Protected methods and attributes can be accessed by subclasses and other classes within the same module, while private methods and attributes can only be accessed within the class that defines them.

It is worth noting that even though private methods and attributes cannot be accessed from outside the class, they can still be accessed with a bit of work using name mangling. Name mangling is the process of adding a class-specific prefix to the name of a private method or attribute to make it harder to access from outside the class. However, this should generally be avoided as it can lead to confusion and make the code harder to maintain.

Here’s an example code to demonstrate access specifiers in Python:

class Student:
    def __init__(self, name, roll_no, branch):
        self.__name = name
        self._roll_no = roll_no
        self.branch = branch
        
    def display_details(self):
        print("Name:", self.__name)
        print("Roll No:", self._roll_no)
        print("Branch:", self.branch)

# create object of Student class
student = Student("John", 101, "CSE")

# try to access private member
print(student.__name) # Error: 'Student' object has no attribute '__name'

# try to access protected member
print(student._roll_no) # Output: 101

# access public member
student.display_details() # Output: Name: John, Roll No: 101, Branch: CSE

In this example, we have a Student class that has three attributes – __name (private), _roll_no (protected), and branch (public). The __init__ method initializes these attributes with the values passed as arguments. The display_details method is a public method that displays the values of all the attributes. We can access the public method and protected member directly from the object of the Student class. However, we cannot access the private member directly, and it raises an error.

55. How to create an empty class in Python?

To create an empty class in Python, you can use the pass statement inside the class definition. This will create a class with no attributes or methods. Here is an example:

class MyClass:
    pass

This will create a class named MyClass with no attributes or methods.

An empty class in Python can be useful as a placeholder for future implementation or as a base class for other classes. It is also a common way to define abstract classes that provide a template for subclasses to implement their own methods.

In Python, classes are a way to create user-defined data types that can hold attributes and methods. Attributes are variables that hold data, while methods are functions that operate on that data. By creating a class, you can define a new data type with its own attributes and methods.

The pass statement is a null operation in Python that does nothing. It is often used as a placeholder in situations where a statement is required syntactically, but no action needs to be taken.

56. What does the object() function do?

The object() function in Python returns a new empty object. It is often used as a base for creating new objects with custom attributes and methods.

However, calling object() directly does not provide much functionality. It is typically used as a parent class for other classes, which allows them to inherit some of the built-in functionality of Python objects.

For example, if we want to create a new class called MyClass that inherits from object(), we can define it like this:

class MyClass(object):
    pass

In this example, we create a new class called MyClass that inherits from object(). This allows MyClass to have access to some of the built-in functionality of Python objects, such as the ability to be used in conditional statements and as a dictionary key.

57. Do we need to declare variables with data types in Python?

In Python, you do not need to declare variables with data types. Python is a dynamically-typed language, which means that the data type of a variable is inferred at runtime based on the value assigned to it. This means that you can assign any type of value to a variable, and Python will automatically determine the appropriate data type. For example, you can assign an integer to a variable, and then assign a string to the same variable without any issues.

However, it is important to note that Python still has data types, and variables do have a data type associated with them at runtime. The difference is that you do not need to explicitly declare the data type when defining a variable.

This dynamic typing feature of Python makes it easier to write and read code, as you do not need to worry about data types and can focus on the logic of the program. However, it also requires careful attention to variable naming and documentation, as the data type of a variable may not always be immediately obvious.

58. How can we create a constructor in Python programming?

In Python, we can create a constructor method by defining a method named __init__. This method is called when an object is created, and it initializes the object’s attributes with the values passed as arguments. The self parameter refers to the object itself and is automatically passed to the constructor method.

Here’s an example code to demonstrate how to create a constructor in Python:

class Car:
    def __init__(self, make, model, year):
        self.make = make
        self.model = model
        self.year = year

    def display_details(self):
        print("Make:", self.make)
        print("Model:", self.model)
        print("Year:", self.year)

# create object of Car class
car = Car("Honda", "City", 2022)

# call display_details method to display the car details
car.display_details() # Output: Make: Honda, Model: City, Year: 2022

In this example, we have a Car class that has three attributes – make, model, and year. The __init__ method initializes these attributes with the values passed as arguments. The display_details method is a public method that displays the values of all the attributes. We can create an object of the Car class and call the display_details method to display the car details.

59. What do you understand about Tkinter?

The selected text is a question that asks for information about Tkinter. Tkinter is a Python library used for creating graphical user interfaces (GUIs) that allows developers to create windows, buttons, and other visual elements for their programs. It is a widely used library for building desktop applications with Python.

Here are some of the main features of Tkinter:

• Cross-platform: Tkinter works on different operating systems like Windows, macOS, and Linux.
• Easy to use: Tkinter provides a simple and intuitive interface for creating GUIs. It also comes with a wide range of pre-built widgets that can be used out of the box.
• Customizable: Tkinter allows developers to customize the look and feel of their GUIs by modifying the properties of widgets like colors, fonts, and sizes.
• Event-driven: Tkinter uses an event-driven programming model, which means that GUI elements respond to user actions like mouse clicks and keyboard inputs by triggering events that can be handled by the program.

To start using Tkinter in your Python programs, you need to import the library and create a main window object. Once you have the main window object, you can add widgets like buttons, labels, and entry fields to it, and configure their properties and behavior.

60. Is Python fully Object Oriented?

Python is an object-oriented programming language, but some argue that it is not fully object-oriented because it allows for procedural programming as well.

However, Python does support many important object-oriented concepts like inheritance, polymorphism, encapsulation, and abstraction. These concepts are important for creating modular, reusable, and maintainable code, and are widely used in many programming languages.

In addition to its object-oriented features, Python also has a strong focus on simplicity, readability, and ease of use. This has made it a popular choice for a wide range of applications, from web development and data analysis to scientific computing and machine learning.

61. What are difference between NumPy and SciPy?

NumPy and SciPy are both Python libraries that are used for scientific computing, but they have some differences. Here are 10 points of differentiation between NumPy and SciPy presented in a table format:

62. Explain the use of the ‘with‘ statement.

The ‘with‘ statement in Python is used to simplify code that uses the same object over and over again by eliminating the need to repeatedly reference it. It does this by temporarily binding a variable to the object, within the scope of the ‘with’ statement. The syntax for using the ‘with’ statement is as follows:

with expression [as variable]:
with-block

Here, expression is any Python expression that returns an object that supports the context management protocol. The optional ‘as’ clause allows us to assign a variable name to the object temporarily bound.

The with-block is a block of code that is executed within the context of the object. Once the block is exited, the temporary variable is automatically unbound from the object, regardless of whether an exception was raised or not.

The ‘with’ statement is commonly used when working with files, as it allows us to automatically close the file once we are done with it, even if an exception is raised. Here is an example of how to use the ‘with’ statement to read the contents of a file:

with open('file.txt', 'r') as f:
data = f.read()
print(data)

In this example, the ‘open’ function is used to open the file ‘file.txt‘ in read mode, and the resulting file object is temporarily bound to the variable ‘f’. The ‘read’ method is then called on the file object to read the contents of the file into the variable ‘data’. Finally, the contents of the file are printed to the console using the ‘print’ statement.

Once the ‘with’ block is exited, the file is automatically closed, regardless of whether an exception was raised or not. This ensures that the file is always properly closed, which is important for avoiding resource leaks and maintaining the stability of the program.

63. What are the differences between Python 2.x and Python 3.x?

Here are the main differences between Python 2.x and Python 3.x:

64. Which programming language is a good choice between Java and Python?

The choice between Java and Python depends on the specific needs of the project. Java is better for large-scale enterprise applications, while Python is better for data analysis and scripting. Both languages have their own strengths and weaknesses, so it’s important to consider the requirements and constraints of the project before making a decision.

To make the best decision, it’s important to evaluate the needs and requirements of the project. Java is a statically-typed language that is better suited for large-scale enterprise applications. It offers strong support for concurrency and multithreading, making it ideal for complex systems that require high performance and scalability.

Python, on the other hand, is a dynamically-typed language that is better suited for data analysis and scripting. It offers a wide range of libraries and tools for scientific computing, machine learning, and data visualization, making it ideal for data-driven projects.

Both languages have their own strengths and weaknesses, so it’s important to consider the specific needs of the project before making a decision. For example, if the project requires high performance and scalability, Java may be the better choice. If the project requires data analysis and visualization, Python may be the better choice.

Ultimately, the choice between Java and Python depends on the specific requirements and constraints of the project. By carefully evaluating these factors and considering the strengths and weaknesses of each language, developers can make an informed decision that will lead to the most successful outcome.

65. What is a negative index in Python and why are they used?

In Python, negative indexing is used to access elements from the end of a list or a string. The index -1 refers to the last element, -2 refers to the second-to-last element, and so on. Negative indexing is useful when you want to access elements from the end of a sequence without knowing its length.

For example, if you have a list my_list = [1, 2, 3, 4, 5], you can access the last element using my_list[-1], which will return 5. Similarly, you can access the second-to-last element using my_list[-2], which will return 4.

Negative indexing can also be used with string slicing. For instance, if you have a string my_string = "Hello, World!", you can extract the last character of the string using my_string[-1], which will return !. You can also extract the substring "World" using my_string[-6:-1].

66. How does Python do Compile-time and Run-time code checking?

Python is an interpreted language, which means that it does not have a separate compilation step. Therefore, it does not perform compile-time code checking in the traditional sense. Instead, Python checks for errors during the execution of the program, which is known as run-time code checking. This means that syntax errors, as well as other types of errors, will not be detected until the code is executed. However, Python does perform some level of run-time type checking to ensure that operations are performed on objects of the correct type.

While Python does not have a separate compilation step, it does have a bytecode compilation step that occurs when a Python script is imported or executed. During this step, the Python interpreter compiles the source code into bytecode, which is then executed by the Python virtual machine.

Python also has a number of tools and libraries that can be used for static analysis of code, which can help detect errors before the code is executed. For example, the pylint and flake8 libraries can be used to check for coding standards violations, syntax errors, and other common issues.

67. What is the shortest method to open a text file and display its content?

The shortest method to open a text file and display its content in many programming languages is to use a few lines of code. For example, in Python you can use the following code:

with open('filename.txt', 'r') as file:
     print(file.read())

This will open the file, read its content and print it to the console.

Regarding the rest of the text, it is a Notion document with a collection of Python interview questions and answers, along with some examples of Python programming problems.

The document starts by discussing Python’s features, such as dynamic typing, object-oriented programming, and support for multiple inheritance. It also covers the differences between Python 2.x and Python 3.x, and the advantages and disadvantages of using Java versus Python.

The document then goes on to provide a variety of Python interview questions, covering topics such as file handling, string manipulation, data structures, and algorithms. For each question, there is a detailed answer that explains the concept being tested and provides an example solution.

Finally, the document includes some programming examples that demonstrate common tasks such as sorting, counting characters, and checking for prime numbers. These examples are designed to help readers practice their Python skills and gain a deeper understanding of the language.

68. What is the usage of enumerate() function in Python?

The enumerate() function in Python is used to iterate over a sequence, such as a list or tuple, and keep track of the index of the current item as you go.

This is useful when you need to access both the index and the value of each item in the sequence. The enumerate() function returns a tuple containing the current index and the current item at each iteration.

Here’s an example of how to use the enumerate() function:

my_list = ['apple', 'banana', 'orange']
for index, item in enumerate(my_list):
print(index, item)

This code will iterate over the list my_list and print out the index and value of each item. The output will be:

0 apple
1 banana
2 orange

As you can see, the enumerate() function makes it easy to iterate over a sequence and keep track of the index of each item. It is a useful tool for many Python programming tasks.

69. How Do You Get Indices of N Maximum Values in a Numpy Array?

To get the indices of the N maximum values in a numpy array, you can use the argsort() method to get the indices that would sort the array, and then select the last N indices. Alternatively, you can use the np.argpartition() method to partition the array into the N largest values and the remaining values, and then get the indices of the N largest values using argsort().

Here is an example of using argsort() to get the indices of the N maximum values in a numpy array:

import numpy as np
arr = np.array([10, 5, 8, 20, 9])
n = 3
Get the indices that would sort the array
sorted_indices = np.argsort(arr)
Select the last N indices
n_max_indices = sorted_indices[-n:]
print(n_max_indices) # Output: [3 0 4]

In this example, we create a numpy array arr with 5 elements. We want to get the indices of the 3 maximum values, so we set n to 3. We then use the argsort() method to get the indices that would sort the array in ascending order. Since we want the indices of the maximum values, we select the last 3 indices of the sorted array using slicing. Finally, we print the resulting indices.

Alternatively, you can use the np.argpartition() method to partition the array into the N largest values and the remaining values, and then use argsort() to get the indices of the N largest values:

import numpy as np
arr = np.array([10, 5, 8, 20, 9])
n = 3

Partition the array into the N largest values and the remaining values

partitioned_indices = np.argpartition(arr, -n)
n_max_indices = partitioned_indices[-n:]
Get the indices of the N largest values
sorted_indices = n_max_indices[np.argsort(arr[n_max_indices])]
print(sorted_indices) # Output: [3 0 4]

In this example, we use argpartition() to partition the array arr into the N largest values and the remaining values. We then select the indices of the N largest values using slicing. Finally, we use argsort() to get the indices of the N largest values in ascending order, and print the resulting indices.

Both methods are efficient ways to get the indices of the N maximum values in a numpy array.

70. How Can You Copy Objects in Python?

In Python, you can copy objects using the copy() method or the deepcopy() method. The copy() method creates a shallow copy, which means that the new object points to the same memory location as the original object. The deepcopy() method creates a deep copy, which means that the new object has its own memory location and any changes made to the new object do not affect the original object.

To use the copy() method, you simply call the method on the object you want to copy. Here’s an example:

original_list = [1, 2, 3, 4]
new_list = original_list.copy()
print(new_list) # Output: [1, 2, 3, 4]

In this example, we create a list original_list with four elements. We then use the copy() method to create a new list new_list that is a shallow copy of original_list. We print the new list to confirm that it has been successfully copied.

To use the deepcopy() method, you need to import the copy module from the standard library, and then call the deepcopy() method on the object you want to copy. Here’s an example:

import copy
original_list = [[1, 2], [3, 4]]
new_list = copy.deepcopy(original_list)
print(new_list) # Output: [[1, 2], [3, 4]]

In this example, we create a nested list original_list with two sublists. We then import the copy module and use the deepcopy() method to create a new list new_list that is a deep copy of original_list. We print the new list to confirm that it has been successfully copied.

71. Explain **kwargs and *args?

In Python, *args and **kwargs are used to pass a variable number of arguments to a function. *args is used to pass a variable number of non-keyword arguments to a function, while **kwargs is used to pass a variable number of keyword arguments to a function. The name args and kwargs are not mandatory, but they are commonly used.

• args is used to pass a tuple of non-keyword arguments to a function. This is useful when you don’t know how many arguments will be passed to the function, or if you want to pass a variable number of arguments. Here’s an example:

def my_function(*args):
for arg in args:
print(arg)
my_function(1, 2, 3)

In this example, the my_function() function takes *args as a parameter, which allows it to accept a variable number of non-keyword arguments. When the function is called with three arguments, it prints each argument to the console.

• *kwargs is used to pass a dictionary of keyword arguments to a function. This is useful when you want to pass a variable number of keyword arguments, or if you want to pass arguments in a specific order. Here’s an example:

def my_function(**kwargs):
    for key, value in kwargs.items():
        print(key, value)
        my_function(name='John', age=30, city='New York')

In this example, the my_function() function takes **kwargs as a parameter, which allows it to accept a variable number of keyword arguments. When the function is called with three keyword arguments, it prints each key-value pair to the console.

72. How to capitalize the first letter of the string?

The capitalize() method in Python can be used to capitalize the first letter of a string. Here’s an example:

my_string = "hello, world!"
capitalized_string = my_string.capitalize()
print(capitalized_string)

In this example, we create a string my_string with the value “hello, world!”. We then use the capitalize() method to create a new string capitalized_string with the first letter capitalized. Finally, we print the new string to the console.

The output of this code will be:

Hello, world!

73. What is the purpose of ‘not’, ‘is’, and ‘in’ operators?

The ‘not’ operator is used to reverse the boolean value of a condition. The ‘is’ operator is used to check if two objects have the same identity. The ‘in’ operator is used to check if a value is present in a sequence, such as a list or a string.

For example, suppose we have a list of numbers and we want to check if the number 10 is not in the list:

my_list = [1, 2, 3, 4, 5]
if 10 not in my_list:
print("10 is not in the list")

In this example, we use the ‘not in’ operator to check if the value 10 is not in the list my_list. Since 10 is not in the list, the condition evaluates to True and the message “10 is not in the list” is printed to the console.

The ‘is’ operator is used to check if two objects have the same identity, which means they occupy the same memory location. It is different from the ‘==’ operator, which checks if two objects have the same value. Here is an example:

x = [1, 2, 3]
y = [1, 2, 3]
if x is y:
    print("x and y have the same identity")
else:
   print("x and y do not have the same identity")

In this example, we create two lists x and y that contain the same values. However, since they occupy different memory locations, the ‘is’ operator returns False and the message “x and y do not have the same identity” is printed to the console.

Finally, the ‘in’ operator is used to check if a value is present in a sequence, such as a list or a string. Here’s an example:

my_list = [1, 2, 3, 4, 5]if 3 in my_list:
    print("3 is in the list")
else:
    print("3 is not in the list")

In this example, we use the ‘in’ operator to check if the value 3 is in the list my_list. Since 3 is in the list, the condition evaluates to True and the message “3 is in the list” is printed to the console.

74. In Python, how do you remark numerous lines?

In Python, you can remark numerous lines by enclosing them in triple quotes (”’ or “””) at the beginning and end of the block of text. This turns the block of text into a multiline string, effectively commenting it out.

Here’s an example:

'''
This is a block of code that has been commented out.
It can contain multiple lines of code.
'''
print("This line of code will be executed.")

In this example, the block of code enclosed in triple quotes is commented out, so it will not be executed. The print statement below the block of code will be executed, however.

75. What method will you use to convert a string to all lowercase?

To convert a string to all lowercase in Python, you can use the lower() method. For example: my_string.lower() will return a lowercase version of my_string.

The lower() method is a built-in Python method that takes no arguments and returns a new string with all uppercase characters converted to lowercase. It does not modify the original string.

Here’s an example:

my_string = "ThIs Is A StRiNg"
lowercase_string = my_string.lower()
print(lowercase_string)

In this example, we create a string my_string with mixed case characters. We then use the lower() method to create a new string lowercase_string that is all lowercase. Finally, we print the new string to the console.

The output of this code will be:

this is a string

76. Why isn’t all the memory deallocated when Python exits?

Python uses automatic memory management, meaning that the interpreter deallocates memory that is no longer used by the program. However, some memory may not be deallocated at the end of the program if there are still references to objects in memory. Additionally, some objects may have circular references, which can prevent the memory from being deallocated. Python provides tools like the gc module to help manage memory deallocation.

77. Explain the split(), sub(), and subn() methods of the Python “re” module.

• split(): This method splits a string into a list of substrings based on a regular expression pattern. The split is performed at every match of the pattern.
• sub(): This method replaces one or more matches of a pattern in a string with a replacement string. It returns the modified string.
• subn(): This method is similar to sub(), but it also returns the number of replacements made in the string.

For example, if we have the following string:

my_string = “The quick brown fox jumps over the lazy dog”

We can use the split() method to split the string into a list of words:

word_list = my_string.split()
print(word_list)

This will output:

['The', 'quick', 'brown', 'fox', 'jumps', 'over', 'the', 'lazy', 'dog']

We can also use a regular expression pattern to split the string based on a specific delimiter. For example, to split the string based on spaces and commas, we can use the following code:

my_string = "The,quick,brown fox jumps over the lazy dog"
word_list = re.split(',| ', my_string)
print(word_list)

This will output:

['The', 'quick', 'brown', 'fox', 'jumps', 'over', 'the', 'lazy', 'dog']

The sub() method can be used to replace all occurrences of a pattern in a string with a replacement string. For example:

my_string = "The quick brown fox jumps over the lazy dog"
new_string = re.sub('fox', 'cat', my_string)
print(new_string)

This will output:

The quick brown cat jumps over the lazy dog

The subn() method is similar to sub(), but it also returns the number of replacements made in the string. For example:

my_string = "The quick brown fox jumps over the lazy dog"
new_string, count = re.subn('fox', 'cat', my_string)
print(new_string)
print(count)

This will output:

The quick brown cat jumps over the lazy dog
1

78. What are the difference between deep and shallow copy?

Here is a table differentiating between deep and shallow copy:

79. How to work with transitive dependencies?

Transitive dependencies are libraries that are required by another library that your project depends on. To work with transitive dependencies, you need to include them in your project along with the direct dependencies. Most build tools like Maven or Gradle will automatically manage transitive dependencies for you. However, it’s important to keep track of them and make sure that you’re using the correct versions to avoid conflicts or unexpected behavior.

If you are not using a build tool, you can manually add the transitive dependencies to your project’s classpath or package them with your application. It’s important to ensure that the dependencies are compatible with each other and with the version of the direct dependency that you are using.

To avoid conflicts or unexpected behavior, it’s also a good idea to explicitly specify the versions of your direct dependencies and transitive dependencies in your project configuration file. This will ensure that the correct versions are used and that there are no version conflicts between dependencies.

80. What is MRO in Python? How does it work?

MRO stands for Method Resolution Order in Python. It is the order in which Python looks for methods in a hierarchy of classes, when there are multiple inheritance paths. The MRO algorithm is used to resolve any potential conflicts that arise due to multiple inheritance. The MRO is determined by the C3 linearization algorithm, which creates a consistent order and ensures that a class will be visited only once. This order is used by Python to search for a method or attribute first in the current class and then in the ancestors of the class.

When a class is defined with multiple inheritance, Python uses the MRO to determine the order in which the parent classes are searched for a given method or attribute. The MRO is important because it determines which method or attribute will be used when there is a conflict between two or more parent classes.

For example, consider the following class hierarchy:

class A:
    def foo(self):
         print("A")class B(A):
    def foo(self):
        print("B")class C(A):
    def foo(self):
        print("C")class D(B, C):
    pass

In this example, we define four classes: A, B, C, and D. Class D inherits from classes B and C, which both inherit from class A. Each class defines a method called foo(). When we create an instance of class D and call the method foo(), Python will use the MRO to determine which version of the method to call.

The MRO for class D is [D, B, C, A]. This means that Python will first look for the method foo() in class D. If it is not found there, Python will look for the method in class B. If it is not found in class B, Python will look for it in class C. Finally, if the method is not found in either class B or class C, Python will look for it in class A.

In this example, the method foo() in class B will be used, because it appears first in the MRO for class D. If we had defined the method foo() differently in one of the parent classes, a different method might have been used.

Python Coding Interview Questions

The following questions test our coding ability in Python.

81. Write a program to produce the Fibonacci series in Python?

To produce a Fibonacci series in Python, you can use a loop to iterate through the sequence and print each number. Here is an example:

n = int(input("Enter the number of terms: "))

# initialize variables
n1, n2 = 0, 1
count = 0

# check if the number of terms is valid
if n <= 0:
   print("Please enter a positive integer")
elif n == 1:
   print("Fibonacci sequence up to",n,":")
   print(n1)
else:
   print("Fibonacci sequence:")
   while count < n:
       print(n1)
       nth = n1 + n2
       # update values
       n1 = n2
       n2 = nth
       count += 1

This program prompts the user to enter the number of terms they want to generate, then uses a loop to iterate through the sequence and print each number.

The Fibonacci sequence is a series of numbers where each number is the sum of the two preceding numbers. The first two numbers in the series are 0 and 1. In the program, we initialize two variables n1 and n2 to 0 and 1, respectively. We also set a variable count to 0 to keep track of the number of terms that have been printed.

The program then checks if the number of terms entered by the user is valid. If the number is less than or equal to 0, the program prints an error message. If the number is 1, the program prints the first term of the sequence. Otherwise, the program enters a loop that continues until the specified number of terms have been printed.

Inside the loop, the program first prints the current term of the sequence, which is stored in the variable n1. It then calculates the next term of the sequence by adding n1 and n2 together and storing the result in a variable nth. Finally, it updates the values of n1 and n2 by setting n1 equal to n2 and n2 equal to nth. The program also increments the value of count by 1 to keep track of the number of terms that have been printed.

82. Write a program in Python to check if a number is prime?

A prime number is a positive integer greater than 1 that has no positive divisors other than 1 and itself. The program should take an input number and check if it is divisible by any number between 2 and the number’s square root. If it is not divisible by any of those numbers, then it is a prime number. The program should return a Boolean value indicating whether the number is prime or not.

To write a program in Python to check if a number is prime or not, we can use the following logic:

• Take input from the user for the number to be checked.
• Check if the number is less than or equal to 1. If yes, it is not a prime number.
• Check if the number is equal to 2. If yes, it is a prime number.
• Check if the number is even. If yes, it is not a prime number.
• Iterate through all odd numbers from 3 to the square root of the number (inclusive).
• If the number is divisible by any of these odd numbers, it is not a prime number.
• If the number is not divisible by any of these odd numbers, it is a prime number.

Here is the Python code that implements this logic:

import math
def is_prime(num):
    if num <= 1:
        return False
    elif num == 2:
        return True
    elif num % 2 == 0:
        return False
    else:
for i in range(3, int(math.sqrt(num))+1, 2):
    if num % i == 0:
        return False
    return True

In this code, we define a function called is_prime() that takes a number as an argument and returns True if it is prime, and False otherwise.

We first check if the number is less than or equal to 1, or if it is even. If either of these conditions is true, we return False, because the number is not prime.

If the number is 2, we return True, because it is the only even prime number.

If the number is odd and greater than 2, we iterate through all odd numbers from 3 to the square root of the number (inclusive), and check if the number is divisible by any of these odd numbers. If it is, we return False, because the number is not prime. If the number is not divisible by any of these odd numbers, we return True, because the number is prime.

83. Write a program in Python to check if a sequence is a Palindrome?

To solve this program in Python that checks if a given sequence is a palindrome, we can use the following approach:

1. Take input from the user for the sequence to be checked.
2. Convert the sequence to lowercase to ignore case sensitivity.
3. Remove all non-alphanumeric characters from the sequence to ignore spaces and other special characters.
4. Reverse the sequence using slicing.
5. Compare the original sequence and the reversed sequence. If they are the same, the sequence is a palindrome.

Here is the Python code that implements this approach:

def is_palindrome(sequence):
    # convert to lowercase and remove non-alphanumeric characters
    sequence = ''.join(filter(str.isalnum, sequence.lower()))
    # reverse the sequence
     reversed_sequence = sequence[::-1]
    # compare the original and reversed sequences
    if sequence == reversed_sequence:
        return True
    else:
        return False

In this code, we define a function called is_palindrome() that takes a sequence as an argument and returns True if it is a palindrome, and False otherwise.

We first convert the sequence to lowercase using the lower() method and remove all non-alphanumeric characters using the filter() method with the str.isalnum function. This ensures that the program ignores case sensitivity and special characters.

We then reverse the sequence using slicing, which creates a new sequence that is the reverse of the original sequence. We store this reversed sequence in a variable called reversed_sequence.

Finally, we compare the original sequence and the reversed sequence using the == operator. If they are the same, the sequence is a palindrome, and we return True. If they are not the same, the sequence is not a palindrome, and we return False.

84. Write a program that will count the number of capital letters in a file. Your code should work even if the file is too big to fit in memory.

To solve this question, we need to read the file in chunks instead of reading the entire file into memory at once. We can use the open() function in Python to open the file and read it in chunks.

Here is an example Python code that counts the number of capital letters in a file:

def count_caps(filename):
    count = 0
    with open(filename, 'rb') as f:
    while True:
         chunk = f.read(1024) # read 1024 bytes at a time
    if not chunk:
        break
     for byte in chunk:
         if 65 <= byte <= 90: # ASCII range of capital letters
         count += 1
    return count

In this code, we define a function called count_caps() that takes a filename as an argument and returns the number of capital letters in the file.

We use the with statement to open the file in binary mode ('rb') and read it in chunks of 1024 bytes at a time. This ensures that we don’t read the entire file into memory at once.

We then iterate over each byte in the chunk and check if it falls within the ASCII range of capital letters (65-90). If it does, we increment the count variable.

Finally, we return the count variable, which contains the total number of capital letters in the file.

85. Write a sorting algorithm for a numerical dataset in Python?

There are several sorting algorithms that can be used to sort a numerical dataset in Python, such as Bubble Sort, Insertion Sort, Selection Sort, Merge Sort, Quick Sort, and Heap Sort. Here’s an example implementation of the Bubble Sort algorithm in Python:

def bubble_sort(arr):
    n = len(arr)
    for i in range(n):
         for j in range(0, n-i-1):
              if arr[j] > arr[j+1] :
                  arr[j], arr[j+1] = arr[j+1], arr[j]

This algorithm compares adjacent elements in the list and swaps them if they are in the wrong order. It repeats this process until the list is sorted.

The bubble_sort() function takes an array as input and sorts it in place using the bubble sort algorithm.

The for loop iterates over the array n times, where n is the length of the array. On each iteration, the inner for loop iterates over the array from the first element to the n-i-1th element. This is because the largest element in the array will “bubble up” to the end of the array on each pass, so we don’t need to compare it again in subsequent iterations.

Inside the inner for loop, we compare adjacent elements in the array. If the left element is greater than the right element, we swap them using tuple unpacking. This ensures that the smaller element “bubbles up” to the left, closer to its correct position in the sorted array.

After n iterations of the outer for loop, the array will be sorted in ascending order.

86. How will you access the dataset of a publicly shared spreadsheet in CSV format stored in Google Drive?

To access a publicly shared CSV format dataset stored in Google Drive, you can use the file ID or the file URL. In both cases, you will need to ensure that the file is publicly shared and that the sharing settings allow anyone with the link to view the file. Once you have the file ID or URL, you can use it to download the dataset using a tool or library that can read CSV files, such as pandas or the csv module in Python.

Here are the steps to access a publicly shared CSV format dataset stored in Google Drive:

• Make sure the file is publicly shared: To access a CSV format dataset stored in Google Drive, you need to ensure that the file is publicly shared. You can do this by opening the file in your Google Drive account, clicking the “Share” button, and setting the sharing settings to “Anyone with the link can view.” This will generate a link that you can use to access the file.
• Get the file ID or URL: Once the file is publicly shared, you can get the file ID or URL. To get the file ID, open the file in your Google Drive account, and the ID will be the string of letters and numbers in the URL after the “id=” parameter. To get the file URL, copy the link that you generated in step 1.
• Download the dataset: Once you have the file ID or URL, you can use it to download the dataset using a library or tool that can read CSV files, such as pandas or the csv module in Python. Here is an example Python code that uses pandas to download a CSV format dataset from Google Drive:

import pandas as pd
file_id = 'your_file_id_here'
url = f'https://drive.google.com/uc?id={file_id}'
df = pd.read_csv(url)

In this code, we define a variable file_id that contains the file ID of the dataset in Google Drive. We then construct the file URL using the file ID and the https://drive.google.com/uc?id= prefix. We pass this URL to the pd.read_csv() function in pandas, which reads the CSV file into a pandas DataFrame.

87. Write a Program to convert date from ‘yyyy-mm-dd‘ format to ‘dd-mm-yyyy‘ format?

Here is an example Python code that converts a date from yyyy-mm-dd format to dd-mm-yyyy format:

from datetime import datetime
def convert_date(date_str):
    date_obj = datetime.strptime(date_str, '%Y-%m-%d')
    return date_obj.strftime('%d-%m-%Y')

In this code, we define a function called convert_date() that takes a date string in the yyyy-mm-dd format as input and returns the same date string in the dd-mm-yyyy format.

We use the datetime.strptime() method to convert the date string to a datetime object. The first argument of this method is the input string, and the second argument is the format string that specifies the format of the input string.

We then use the strftime() method to format the datetime object as a string in the dd-mm-yyyy format. The argument of this method is a format string that specifies the desired output format.

88. Write a Program to match a string that has the letter ‘a’ followed by 4 to 8 ‘b’s?

Here is an example Python code that matches a string that has the letter ‘a’ followed by 4 to 8 ‘b’s:

import re
def match_string(string):
    pattern = r'^a[b]{4,8}$'
    match = re.match(pattern, string)
    if match:
        return True
    else:
        return False

In this code, we define a function called match_string() that takes a string as input and returns True if the string matches the pattern, and False otherwise.

We use the re module in Python to work with regular expressions. The r before the string pattern indicates that it is a raw string, which is used to avoid any special characters being interpreted in the pattern.

The regular expression pattern ^a[b]{4,8}$ matches a string that begins with the letter “a” followed by 4 to 8 “b”s. The ^ character indicates the start of the string, and the $ character indicates the end of the string. The [b]{4,8} part of the pattern matches 4 to 8 “b”s.

We then use the re.match() method to match the pattern to the input string. If the match is successful, the method returns a match object. If the match is not successful, the method returns None.

Finally, we check if the match object is not None, and return True if it is not and False otherwise.

89. Write a program which takes a sequence of numbers and checks if all numbers are unique?

To solve this problem, we can use a Python set to keep track of the unique numbers in the sequence. We can iterate through the sequence and add each number to the set. If a number is already in the set, then we know that it is not unique and we can return False. If we reach the end of the sequence without finding any duplicates, then we know that all the numbers are unique and we can return True.

Here’s an example Python code that checks if a sequence of numbers is unique:

def is_unique(seq):
    seen = set()
    for num in seq:
        if num in seen:
            return False
        seen.add(num)
    return True

In this code, we define a function called is_unique() that takes a sequence of numbers as input and returns True if all the numbers in the sequence are unique, and False otherwise.

We create an empty set called seen to keep track of the unique numbers in the sequence. We then iterate through the sequence using a for loop, and check if each number is already in the seen set using the in operator. If the number is already in the set, we know that it is not unique and we can return False. If the number is not in the set, we add it to the set using the add() method.

If we reach the end of the sequence without finding any duplicates, we know that all the numbers are unique and we can return True.

90. Write a program for counting the number of every character of a given text file?

To write a program that counts the number of occurrences of each character in a given text file, we can use a dictionary to keep track of the counts for each character. We can iterate through each character in the file, and if the character is not already in the dictionary, we can add it with a count of 1. If the character is already in the dictionary, we can increment its count by 1.

Here is an example Python code that counts the number of occurrences of each character in a text file:

def count_chars(filename):
    char_counts = {}
    with open(filename) as f:
        for line in f:
            for char in line:
                if char in char_counts:
                    char_counts[char] += 1
                else:
                    char_counts[char] = 1
    return char_counts

In this code, we define a function called count_chars() that takes a filename as input and returns a dictionary containing the number of occurrences of each character in the file.

We create an empty dictionary called char_counts to store the counts for each character. We use the with statement to open the file, which ensures that the file is closed properly after we are done reading it.

We then iterate through each line in the file using a for loop, and iterate through each character in the line using another for loop. We check if the character is already in the char_counts dictionary using the in operator. If the character is already in the dictionary, we increment its count by 1. If the character is not in the dictionary, we add it with a count of 1 using the dictionary’s [] notation.

Finally, we return the char_counts dictionary, which contains the number of occurrences of each character in the file.

91. Write a program to check and return the pairs of a given array A whose sum value is equal to a target value N in points?

To solve this problem, we can use a nested loop to compare each pair of elements in the array and check if their sum is equal to the target value. If a pair is found, we can add it to a list of points and return the list at the end.

Here’s an example Python code that finds all pairs of elements in an array whose sum is equal to a target value:

def find_pairs(array, target):
    pairs = []
    for i in range(len(array)):
        for j in range(i+1, len(array)):
            if array[i] + array[j] == target:
                pairs.append((array[i], array[j]))
    return pairs

In this code, we define a function called find_pairs() that takes an array and a target value as input, and returns a list of points that represent pairs of elements in the array whose sum is equal to the target value.

We create an empty list called pairs to store the pairs of elements that we find. We then use a nested for loop to iterate through each pair of elements in the array. We start the inner loop at i+1 to avoid comparing an element to itself and to avoid comparing the same pair of elements twice.

We check if the sum of the two elements is equal to the target value using the == operator. If it is, we add the pair to the pairs list using the tuple notation (array[i], array[j]).

Finally, we return the pairs list, which contains all pairs of elements in the array whose sum is equal to the target value.

92. What is the easiest way to calculate percentiles when using Python?

Use the numpy library function percentile(). numpy is a widely used library for scientific computing in Python and can be easily installed using pip. The percentile() function is a convenient way to calculate percentiles of a data set in Python.

The function takes three arguments: the data set, the percentile to calculate (as a decimal), and the interpolation method. The interpolation method specifies how to calculate percentiles for data sets with irregularly spaced values. The default method is linear, which is appropriate for data sets with regularly spaced values.

To use the percentile() function, you need to import the numpy library at the beginning of your script. Here’s an example Python code that calculates the 90th percentile of a data set using the percentile() function:

import numpy as np

data = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
pct = 0.9
result = np.percentile(data, pct*100, interpolation='nearest')
print(result)

In this code, we import the numpy library using the import statement. We define a list called data that contains the data set that we want to calculate the percentile for. We define a variable pct that contains the percentile we want to calculate, as a decimal. We call the percentile() function with the data, pct*100 (to convert the decimal to a percentage), and interpolation='nearest' arguments. We store the result in a variable called result. Finally, we print the result using the print() function.

The percentile() function is a powerful tool for calculating percentiles of data sets in Python. By using the numpy library, you can easily perform advanced statistical analyses on your data sets.

93. Write a Python program to calculate the sum of a list of numbers?

In Python, this can be solve using a loop to iterate through the list and add each number to a running total variable. The final total can be returned or printed to the console.

The solution to the task can be implemented as follows:

def sum_list(numbers):
    total = 0
    for num in numbers:
        total += num
    return total

In this code, we define a function called sum_list() that takes a list of numbers as input and returns the sum of the numbers.

We create a variable called total and initialize it to 0. We then use a for loop to iterate through each number in the list. We add each number to the total variable using the += operator.

Finally, we return the total variable, which contains the sum of the numbers in the list.

94. Create a program that combines two dictionaries. If you locate the same keys during combining, you can sum the values of these similar keys. Create a new dictionary?

To Solve this, we can create a function that takes in the two dictionaries as arguments. We can then iterate through all the keys in both dictionaries using a for loop, and add their values together if the keys are the same. We can add the keys and values to a new dictionary, using the setdefault() method to create a new key if it doesn’t already exist. Finally, we can return the new dictionary.

Here’s an example Python code that merges two dictionaries:

def merge_dicts(dict1, dict2):
    result = {}
    for key in dict1.keys():
        result.setdefault(key, 0)
        result[key] += dict1[key]
    for key in dict2.keys():
        result.setdefault(key, 0)
        result[key] += dict2[key]
    return result

In this code, we define a function called merge_dicts() that takes two dictionaries as input and returns a new dictionary that merges the two dictionaries.

We create an empty dictionary called result to store the merged dictionary. We use two for loops to iterate through each key in the two dictionaries. We use the setdefault() method to create a new key in the result dictionary if it doesn’t already exist. We then add the values of the keys together if the keys are the same.

Finally, we return the result dictionary, which contains all the keys and values from the original two dictionaries merged together.

95. Create a program to add two integers >0 without using the plus operator?

There are alternative operators and bitwise manipulations that can be used to perform addition, such as the bitwise OR and AND operators and left shifting. You can also use the Python built-in function sum() to add two numbers together by passing them as a list or tuple. The implementation will depend on the specific requirements.

Here are some examples of how you could implement the program to add two positive integers without using the plus operator:

Using the bitwise OR and AND operators:

def add(a, b):
    while b != 0:
        carry = a & b
        a = a ^ b
        b = carry << 1
    return a

In this code, we define a function called add() that takes two positive integers as input and returns their sum. We use a while loop to continue adding the numbers until there is no carry left.

We use the bitwise OR operator | to calculate the carry, and the bitwise XOR operator ^ to calculate the sum. We then shift the carry to the left by one bit using the left shift operator << and continue the loop.

Finally, we return the value of a, which contains the sum of the two input integers.

Using the Python built-in sum() function:

def add(a, b):
    return sum((a, b))

In this code, we define a function called add() that takes two positive integers as input and returns their sum. We pass the input integers as a tuple to the sum() function, which calculates their sum and returns the result.

These are just two examples of how you could implement the program to add two positive integers without using the plus operator. The most appropriate implementation may depend on the specific requirements of the prompt and the constraints of the programming environment.

96. Write a program to print out the 2-table using a while loop?

The 2-table is a multiplication table where each cell contains the product of the row and column numbers. For example, the cell in the second row and third column would contain the number 6 (2 x 3 = 6).

To print out the 2-table using a while loop in Python, we can define two variables row and col to keep track of the current row and column numbers. We can then use a nested while loop to iterate through each row and column, and print out the product of the row and column numbers at each iteration.

Here’s an example Python code that prints out the 2-table using a while loop:

row = 1
while row <= 10:
    col = 1
    while col <= 10:
        product = row * col
        print(product, end=' ')
        col += 1
    print()
    row += 1

In this code, we define a variable row and initialize it to 1. We use a while loop to iterate through each row of the 2-table, stopping when we reach the 10th row.

Inside the outer while loop, we define a variable col and initialize it to 1. We use another while loop to iterate through each column of the 2-table, stopping when we reach the 10th column.

Inside the inner while loop, we calculate the product of the current row and column numbers and store it in a variable called product. We then print out the value of product, followed by a space character, using the print() function with the end argument set to a space character. This ensures that the values are printed on the same line.

After the inner while loop is finished, we print a newline character using the print() function with no arguments. This moves the output to the next line.

Finally, we increment the value of row by 1 and continue the outer while loop.

97. Write a function, which will take in a value and print out if it is even or odd?

For example, you could write a Python function called even_or_odd() that takes a single integer as input and returns the string “Even” or “Odd” depending on whether the input is even or odd. Here is an example implementation of the function:

def even_or_odd(num):
    if num % 2 == 0:
        return "Even"
    else:
        return "Odd"

In this code, we define a function called even_or_odd() that takes a single integer num as input.

We use an if statement to check whether num is divisible by 2 (even) using the modulus operator %. If num is even, the remainder of num divided by 2 will be 0, so the condition num % 2 == 0 will be true. In this case, we return the string “Even”.

If num is not even, the condition num % 2 == 0 will be false, and we will execute the else block. In this case, we return the string “Odd”.

98. Write a program find the minimum and maximum values present in a tuple?

First, create a tuple with the desired values. Then, use the min() and max() functions to find the minimum and maximum values, respectively. The code might look something like this:

tup = (3, 5, 1, 9, 2)
print("Minimum value:", min(tup))
print("Maximum value:", max(tup))

This would output:

Minimum value: 1
Maximum value: 9

99. How to print the star(*) pattern without newline and space?

To print a star pattern without newline and space, we can use nested loops. The outer loop is used for the rows, and the inner loop is used for the columns. Within the inner loop, we can print the star character without adding a newline or space. Here’s an example in Python:

for i in range(5):
    for j in range(5):
        print('*', end='')

This will print a 5×5 square of stars without any whitespace or newlines between them.

100. How to read an 8GB file in Python?

Reading a large file in Python can be done using the read() method of the file object in combination with a loop to read the file in chunks. This can be done for an 8GB file as well. Another approach is to use the mmap() function to map the file into memory and read it from there. However, this approach may not be suitable for files that are larger than the available memory.

When using the read() method to read a large file, it’s important to read the file in chunks instead of all at once to avoid memory errors. This can be done by specifying the number of bytes to read at a time using the read() method. For example, to read a file in chunks of 1MB at a time, we can use the following code:

with open('large_file.txt', 'r') as f:
    while True:
        chunk = f.read(1024*1024) # read 1MB at a time
        if not chunk:
            break
        # process the chunk here

In this code, we use a with statement to open the file in read mode. We then use a while loop to read the file in chunks of 1MB at a time using the read() method. The read() method returns a string containing the characters read from the file, up to the number of bytes specified.

We check if the chunk is empty using the not operator to determine if we have reached the end of the file. If the chunk is empty, we break out of the loop. Otherwise, we process the chunk as desired.

The mmap() function can also be used to map a file into memory and read it from there. This approach can be more efficient for certain types of files, such as binary files. However, it may not be suitable for files that are larger than the available memory, as it requires the entire file to be loaded into memory.

Conclusion

In conclusion, Python has become a highly popular programming language that is used by both beginners and experts in the field. It is a versatile language that can be used for a wide range of applications including data analysis, web development, machine learning, and more.

The top 100 Python interview questions and answers provided in this article cover a wide range of topics including basic concepts, data structures, control structures, functions, modules, classes, and more. It is important to note that these questions are not exhaustive and may not cover all possible scenarios that you may encounter in an interview.

To ace a Python interview, it is important to have a strong foundation in the language and be familiar with its syntax and conventions. Additionally, practicing coding challenges and working on real-world projects can help you gain hands-on experience and showcase your skills to potential employers.

Overall, the key to success in a Python interview is to stay calm, confident, and focused, and to demonstrate your understanding of the language through clear and concise answers.

FAQs for Interview Preparation

1. What are the most common Python interview questions?

The most common Python interview questions cover a wide range of topics such as basic concepts, data structures, control structures, functions, modules, classes, and more. Employers may ask questions related to Python syntax, data types, control statements, and loops, as well as questions about object-oriented programming and Python libraries such as NumPy, Pandas, and Matplotlib. Additionally, employers may ask questions about algorithm design, debugging, and problem-solving skills. It is important to have a strong foundation in the language and be familiar with its syntax and conventions, as well as to practice coding challenges and work on real-world projects to gain hands-on experience and showcase your skills to potential employers.

2. How should I prepare for a Python interview?

To prepare for a Python interview, it is important to review the language’s basic concepts, syntax, and conventions, as well as to practice coding challenges and work on real-world projects to gain hands-on experience. Employers may also ask questions about algorithms, data structures, object-oriented programming, and Python libraries. Additionally, it can be helpful to research the company and the specific position you are interviewing for to understand the types of Python projects and technologies you may be working with. It is also important to stay calm, confident, and focused during the interview and to demonstrate your understanding of the language through clear and concise answers.

3. What topics should I study for an upcoming Python interview?

For an upcoming Python interview, it is important to review the language’s basic concepts such as variables, data types, and control statements. It is also important to have a strong understanding of data structures such as lists, tuples, and dictionaries, as well as functions, modules, and classes. Object-oriented programming concepts such as inheritance, polymorphism, and encapsulation are also common interview topics. Additionally, employers may ask about Python libraries such as NumPy, Pandas, and Matplotlib, as well as algorithm design, debugging, and problem-solving skills. It is important to stay up-to-date with the latest Python trends and technologies and to practice coding challenges and work on real-world projects to gain hands-on experience.

4. Are there specific tips for answering Python interview questions?

Yes, some tips for answering Python interview questions include: preparing for common Python interview questions, practicing coding problems, demonstrating problem-solving skills, and showing experience with Python libraries and frameworks. It’s also important to communicate effectively and clearly with the interviewer.

5. What are the best resources for practicing Python interview questions and answers?

This selection is a question about the best resources for practicing Python interview questions and answers. It is likely part of a larger discussion about preparing for a job interview that involves Python programming. The answer would provide suggestions for websites, books, or other resources that offer sample interview questions and guidance on how to answer them.

6. What are the 5 easy steps to learn Python?

The 5 easy steps to learn Python are:

• Understand the basics of programming
• Choose an appropriate learning resource
• Practice coding regularly
• Join a community or forum of Python programmers
• Build real-life projects to apply your skills

7. How to become an expert Python Programmer?

To become an expert Python programmer, it is important to have a strong foundation in the language’s basic concepts and syntax, as well as to gain hands-on experience by working on real-world projects. It is also important to stay up-to-date with the latest Python trends and technologies, as well as to develop expertise in areas such as data analysis, web development, and machine learning. Networking with other Python developers, contributing to open-source projects, and attending Python conferences and workshops can also help to further develop expertise. Consistent practice and a commitment to continuous learning are key to becoming an expert Python programmer.

8. What are the 4 main uses of Python?

Python is a popular programming language that can be used for a variety of tasks, including web development, data analysis, artificial intelligence, and automation.

It is known for its simplicity, readability, and ease of learning, making it a popular choice for beginners and experienced programmers alike.

Python has a large and active community, which means that there are many resources available for learning and troubleshooting. Additionally, Python has a vast library of modules and packages that can be easily imported into a program to perform specific tasks, such as data manipulation or web scraping.

Many companies are now using Python for their projects, and there is a high demand for Python programmers in the job market. Therefore, learning Python can be a valuable skill for individuals looking to advance their careers in technology.

9. How much Python do I have to learn to get a job?

The amount of Python you need to learn to get a job can vary depending on the specific position and employer. Generally, a strong understanding of the language’s basic concepts such as variables, data types, control statements, functions, and data structures such as lists, tuples, and dictionaries is important. Additionally, having familiarity with Python libraries such as NumPy, Pandas, and Matplotlib, as well as object-oriented programming concepts such as inheritance and encapsulation, can be beneficial. However, it is also important to have hands-on experience through working on real-world projects, as this can showcase your skills to potential employers.

10. Can a fresher get a job at Python?

Yes, a fresher can get a job at Python with the right skills and preparation. Employers may look for a strong foundation in Python’s basic concepts and syntax, as well as hands-on experience through working on real-world projects. Additionally, having familiarity with Python libraries such as NumPy, Pandas, and Matplotlib, as well as object-oriented programming concepts such as inheritance and encapsulation, can be beneficial. Networking with other Python developers, contributing to open-source projects, and attending Python conferences and workshops can also help to increase a fresher’s chances of landing a job in the field.

Happy Learning!!