Python | Check if one dictionary is subset of other

Last Updated : 26 Jul, 2019

Sometimes, while working with Python, we might have a problem in which we need to find, if a particular dictionary is a part of other i.e it is subset of other. A problem that have a huge potential in web development domain, having knowledge of solving can be useful. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using all() + items()
This task can be performed using the combination of above two functions, in which we check for all the items of the subdict with the original dict using all() and fetch it’s each pair using items().

# Python3 code to demonstrate working of
# Check if one dictionary is subset of other
# Using all() + items()
  
# Initialize dictionaries
test_dict1 = {'gfg' : 1, 'is' : 2, 'best' : 3, 'for' : 4, 'CS' : 5}
test_dict2 = {'gfg' : 1, 'is' : 2, 'best' : 3}
  
# printing original dictionaries
print("The original dictionary 1 : " +  str(test_dict1))
print("The original dictionary 2 : " +  str(test_dict2))
  
# Using all() + items()
# Check if one dictionary is subset of other
res = all(test_dict1.get(key, None) == val for key, val
                                 in test_dict2.items())
      
# printing result 
print("Does dict2 lie in dict1 ? : " + str(res))

Output :

The original dictionary 1 : {‘CS’: 5, ‘is’: 2, ‘best’: 3, ‘gfg’: 1, ‘for’: 4}
The original dictionary 2 : {‘is’: 2, ‘best’: 3, ‘gfg’: 1}
Does dict2 lie in dict1 ? : True

Method #2 : Using items() + <= operator
Another alternative to perform the above task can be using the items() along with <= operator. This just checks for less than or all values of all the key value matched.

# Python3 code to demonstrate working of
# Check if one dictionary is subset of other
# Using items() + <= operator
  
# Initialize dictionaries
test_dict1 = {'gfg' : 1, 'is' : 2, 'best' : 3, 'for' : 4, 'CS' : 5}
test_dict2 = {'gfg' : 1, 'is' : 2, 'best' : 3}
  
# printing original dictionaries
print("The original dictionary 1 : " +  str(test_dict1))
print("The original dictionary 2 : " +  str(test_dict2))
  
# Using items() + <= operator
# Check if one dictionary is subset of other
res = test_dict2.items() <= test_dict1.items()
      
# printing result 
print("Does dict2 lie in dict1 ? : " + str(res))

Output :

The original dictionary 1 : {‘CS’: 5, ‘is’: 2, ‘best’: 3, ‘gfg’: 1, ‘for’: 4}
The original dictionary 2 : {‘is’: 2, ‘best’: 3, ‘gfg’: 1}
Does dict2 lie in dict1 ? : True

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