Python – Assign values to initialized dictionary keys

Difficulty Level : Basic
Last Updated : 06 Mar, 2020

Sometimes, while working with python dictionaries, we can have a problem in which we need to initialize dictionary keys with values. We save a mesh of keys to be initialized. This usually happens during web development while working with JSON data. Lets discuss certain ways in which this task can be performed.

Method #1 : Using dict() + zip()
The combination of above methods can be used to perform this task. In this, we allot the list values to already constructed mesh and zip() helps in mapping values as per list index.

# Python3 code to demonstrate working of 
# Assign values to initialized dictionary keys
# using dict() + zip()
    
# initializing dictionary 
test_dict = {'gfg' : '', 'is' : '', 'best' : ''} 
  
# Initializing list 
test_list = ['A', 'B', 'C']
    
# printing original dictionary 
print("The original dictionary is : " + str(test_dict)) 
  
# Assign values to initialized dictionary keys
# using dict() + zip()
res = dict(zip(test_dict, test_list))
    
# printing result  
print("The assigned value dictionary is : " + str(res)) 

Output :

The original dictionary is : {'is': '', 'best': '', 'gfg': ''}
The assigned value dictionary is : {'gfg': 'C', 'best': 'B', 'is': 'A'}

Method #2 : Using loop + zip()
This is extended way in which this task can be performed. In this, we iterate through the zipped list and assign value to dictionary.

# Python3 code to demonstrate working of 
# Assign values to initialized dictionary keys
# using loop + zip()
    
# initializing dictionary 
test_dict = {'gfg' : '', 'is' : '', 'best' : ''} 
  
# Initializing list 
test_list = ['A', 'B', 'C']
    
# printing original dictionary 
print("The original dictionary is : " + str(test_dict)) 
  
# Assign values to initialized dictionary keys
# using loop + zip()
for key, val in zip(test_dict, test_list):
    test_dict[key] = val
    
# printing result  
print("The assigned value dictionary is : " + str(test_dict)) 

Output :

The original dictionary is : {'is': '', 'best': '', 'gfg': ''}
The assigned value dictionary is : {'gfg': 'C', 'best': 'B', 'is': 'A'}

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Python – Assign values to initialized dictionary keys