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Python – Add prefix to each key name in dictionary

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  • Last Updated : 01 Aug, 2020
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Given a dictionary, update its each key by adding prefix to each key.

Input : test_dict = {‘Gfg’ : 6, ‘is’ : 7, ‘best’ : 9}, temp = “Pro”
Output : {‘ProGfg’ : 6, ‘Prois’ : 7, ‘Probest’ : 9}
Explanation : “Pro” prefix added to each key.

Input : test_dict = {‘Gfg’ : 6, ‘is’ : 7, ‘best’ : 9}, temp = “a”
Output : {‘aGfg’ : 6, ‘ais’ : 7, ‘abest’ : 9}
Explanation : “a” prefix added to each key.

Method #1 : Using dictionary comprehension

This is one of the methods in which this task can be performed. In this we construct new dictionary by performing concatenation of prefix with all keys.

Python3




# Python3 code to demonstrate working of 
# Add prefix to each key name in dictionary
# Using loop
  
# initializing dictionary
test_dict = {'Gfg' : 6, 'is' : 7, 'best' : 9, 'for' : 8, 'geeks' : 11
  
# printing original dictionary
print("The original dictionary is : " + str(test_dict))
  
# initializing prefix 
temp = "Pro"
  
# + operator is used to perform task of concatenation
res = {temp + str(key): val for key, val in test_dict.items()}
  
# printing result 
print("The extracted dictionary : " + str(res)) 

Output

The original dictionary is : {'Gfg': 6, 'is': 7, 'best': 9, 'for': 8, 'geeks': 11}
The extracted dictionary : {'ProGfg': 6, 'Prois': 7, 'Probest': 9, 'Profor': 8, 'Progeeks': 11}

Method #2 : Using f strings + dictionary comprehension

The combination of above functionalities can be used to solve this problem. In this, we perform the task of concatenation using f strings. Works only in >=3.6 versions of Python.

Python3




# Python3 code to demonstrate working of 
# Add prefix to each key name in dictionary
# Using f strings + dictionary comprehension
  
# initializing dictionary
test_dict = {'Gfg' : 6, 'is' : 7, 'best' : 9, 'for' : 8, 'geeks' : 11
  
# printing original dictionary
print("The original dictionary is : " + str(test_dict))
  
# initializing prefix 
temp = "Pro"
  
# dictionary comprehension is used to bind result 
# f strings are used to bind prefix with key
res = {f"Pro{key}": val for key, val in test_dict.items()}
  
# printing result 
print("The extracted dictionary : " + str(res)) 

Output

The original dictionary is : {'Gfg': 6, 'is': 7, 'best': 9, 'for': 8, 'geeks': 11}
The extracted dictionary : {'ProGfg': 6, 'Prois': 7, 'Probest': 9, 'Profor': 8, 'Progeeks': 11}

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