Python dictionary intersection – compare two dictionaries

Python examples to find common items between 2 or more dictionaries i.e. dictionary intersection items.

1. Dictionary intersection using ‘&’ operator

Simplest method is to find intersections of keys, values or items is to use & operator between two dictionaries.

a = { 'x' : 1, 'y' : 2, 'z' : 3 }
b = { 'u' : 1, 'v' : 2, 'w' : 3, 'x'  : 1, 'y': 2 }

set( a.keys() ) & set( b.keys() )   	# Output set(['y', 'x'])

set( a.items() ) & set( b.items() )   	# Output set([('y', 2), ('x', 1)])

2. Set intersection() method

Set intersection() method return a set that contains the items that exist in both set a, and set b.

a = { 'x' : 1, 'y' : 2, 'z' : 3 }
b = { 'u' : 1, 'v' : 2, 'w' : 3, 'x'  : 1, 'y': 2 }

setA = set( a )
setB = set( b )

setA.intersection( setB )  

# Output 
# set(['y', 'x'])

for item in setA.intersection(setB):
    print item

# Output 
#x
#y

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