Python | Extract specific keys from dictionary

Difficulty Level : Basic
Last Updated : 16 May, 2019

We have a lot of variations and applications of dictionary container in Python and sometimes, we wish to perform a filter of keys in dictionary, i.e extracting just the keys which are present in particular container. Let’s discuss certain ways in which this can be performed.

Method #1 : Using dictionary comprehension + items()

This problem can be performed by reconstruction using the keys extracted through items function that wish to be filtered and dictionary function makes the desired dictionary.

# Python3 code to demonstrate
# Extracting specifix keys from dictionary
# Using dictionary comprehension + items()
  
# initializing dictionary
test_dict = {'nikhil' : 1, "akash" : 2, 'akshat' : 3, 'manjeet' : 4}
  
# printing original list
print("The original dictionary : " + str(test_dict))
  
# Using dictionary comprehension + items()
# Extracting specifix keys from dictionary
res = {key: test_dict[key] for key in test_dict.keys()
                               & {'akshat', 'nikhil'}}
  
# print result
print("The filtered dictionary is : " + str(res))

Output :

The original dictionary : {'manjeet': 4, 'akshat': 3, 'akash': 2, 'nikhil': 1}
The filtered dictionary is : {'akshat': 3, 'nikhil': 1}

Method #2 : Using dict()

The dict function can be used to perform this task by converting the logic performed using list comprehension into a dictionary.

# Python3 code to demonstrate
# Extracting specifix keys from dictionary
# Using dict()
  
# initializing dictionary
test_dict = {'nikhil' : 1, "akash" : 2, 'akshat' : 3, 'manjeet' : 4}
  
# printing original list
print("The original dictionary : " + str(test_dict))
  
# Using dict()
# Extracting specifix keys from dictionary
res = dict((k, test_dict[k]) for k in ['nikhil', 'akshat']
                                        if k in test_dict)
  
# print result
print("The filtered dictionary is : " + str(res))

Output :

The original dictionary : {'manjeet': 4, 'akshat': 3, 'akash': 2, 'nikhil': 1}
The filtered dictionary is : {'akshat': 3, 'nikhil': 1}

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