Python – Change type of key in Dictionary list

Last Updated : 10 May, 2020

Sometimes, while working with data, we can have a problem in which we require to change the type of particular keys’ value in list of dictionary. This kind of problem can have application in data domains. Lets discuss certain ways in which this task can be performed.

Input : test_list = [{‘gfg’: 9, ‘best’: (7, 2), ‘is’: ‘4’}, {‘is’: ‘2’}]
Output : [{‘gfg’: 9, ‘best’: (7, 2), ‘is’: 4}, {‘is’: 2}]
Input : test_list = [{‘is’ : ‘98393’}]
Output : [{‘is’ : 98393}]

Method #1 : Using loop
This is brute force way to approach this problem. In this, we iterate for all list elements and dictionary keys and convert the desired dictionary key’s value to required type.

# Python3 code to demonstrate working of 
# Change type of key in Dictionary list
# Using loop
  
# initializing list
test_list = [{'gfg' : 1, 'is' : '56', 'best' : (1, 2)}, 
            {'gfg' : 5, 'is' : '12', 'best' : (6, 2)},
            {'gfg' : 3, 'is' : '789', 'best' : (7, 2)}]
  
# printing original list
print("The original list is : " + str(test_list))
  
# initializing change key 
chnge_key = 'is'
  
# Change type of key in Dictionary list
# Using loop
for sub in test_list:
        sub[chnge_key] = int(sub[chnge_key])
  
# printing result 
print("The converted Dictionary list : " + str(test_list)) 

Output :

The original list is : [{‘is’: ’56’, ‘gfg’: 1, ‘best’: (1, 2)}, {‘is’: ’12’, ‘gfg’: 5, ‘best’: (6, 2)}, {‘is’: ‘789’, ‘gfg’: 3, ‘best’: (7, 2)}]
The converted Dictionary list : [{‘is’: 56, ‘gfg’: 1, ‘best’: (1, 2)}, {‘is’: 12, ‘gfg’: 5, ‘best’: (6, 2)}, {‘is’: 789, ‘gfg’: 3, ‘best’: (7, 2)}]

Method #2 : Using list comprehension
This task can also be performed using list comprehension as a shorthand. In this, we iterate for list in shorter way as above with same approach.

# Python3 code to demonstrate working of 
# Change type of key in Dictionary list
# Using list comprehension
  
# initializing list
test_list = [{'gfg' : 1, 'is' : '56', 'best' : (1, 2)}, 
            {'gfg' : 5, 'is' : '12', 'best' : (6, 2)},
            {'gfg' : 3, 'is' : '789', 'best' : (7, 2)}]
  
# printing original list
print("The original list is : " + str(test_list))
  
# initializing change key 
chnge_key = 'is'
  
# Change type of key in Dictionary list
# Using list comprehension
res = [{key : (int(val) if key == chnge_key else val)
                        for key, val in sub.items()}
                        for sub in test_list]
  
# printing result 
print("The converted Dictionary list : " + str(res)) 

Output :

The original list is : [{‘is’: ’56’, ‘gfg’: 1, ‘best’: (1, 2)}, {‘is’: ’12’, ‘gfg’: 5, ‘best’: (6, 2)}, {‘is’: ‘789’, ‘gfg’: 3, ‘best’: (7, 2)}]
The converted Dictionary list : [{‘is’: 56, ‘gfg’: 1, ‘best’: (1, 2)}, {‘is’: 12, ‘gfg’: 5, ‘best’: (6, 2)}, {‘is’: 789, ‘gfg’: 3, ‘best’: (7, 2)}]

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Python – Change type of key in Dictionary list