Python | Initialize common value to keys

Last Updated : 26 Aug, 2019

Sometimes, while working with Python, we can be confronted with an issue in which we need to assign each key of dictionary with a common value. This type of problem in not occasional but can occur many times while programming. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using defaultdict() + lambda

The defaultdict can be initialized using a function which by default assigns each new key with the common key. This is most recommended way to perform this task.

# Python3 code to demonstrate working of
# Initialize common value to keys
# Using defaultdict()
from collections import defaultdict
  
# Initialize dictionary
test_dict = dict()
  
# printing original dictionary
print("The original dictionary is : " + str(test_dict))
  
# Initialize common value to keys
# Using defaultdict()
res = defaultdict(lambda: 4, test_dict)
res_demo = res['Geeks']
  
# printing result
print("The value of key is :  " + str(res_demo))

Output :

The original dictionary is : {}
The value of key is :  4

Method #2 : Using get() + default value

This method is just a display hack to perform this task. It doesn’t create the actual list, but just prints the default value passed to get function and hence the result.

# Python3 code to demonstrate working of
# Initialize common value to keys
# Using get() + default value
  
# Initialize dictionary
test_dict = dict()
  
# printing original dictionary
print("The original dictionary is : " + str(test_dict))
  
# Initialize common value to keys
# Using get() + default value
res_demo = test_dict.get('Geeks', 4)
  
# printing result
print("The value of key is :  " + str(res_demo))

Output :

The original dictionary is : {}
The value of key is :  4

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Python | Initialize common value to keys