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Python – Reinitialize Value lists to K in Dictionary

  • Last Updated : 22 Jun, 2021

Sometimes, while working with Python dictionary values, we can have a problem in which we need to reinitialize all the values lists of all keys in dictionary to a constant K. This kind of problem can have application in domains which use data, like Machine Learning and Data Science. Let’s discuss certain way in which this task can be performed.
 

Input : test_dict = {‘Gfg’ : [[4, 5], [8, 9, 20], [1, 3, 4, ‘oops’]]} 
Output : {‘Gfg’: [[4, 4], [4, 4, 4], [4, 4, 4, 4]]}
Input : test_dict = {‘Gfg’ : “best”} 
Output : {‘Gfg’ : 4} 
 

Method : Using recursion + type() + dictionary comprehension + items() + loop 
The combination of above functionalities can help to solve this problem. In this, we perform the assignment of values using dictionary comprehension and types are tested using type. The items() is used to extract values from dictionary and to perform to each nesting is handled by recursion.
 

Python3




# Python3 code to demonstrate working of
# Reinitialize Value lists to K in Dictionary
# Using recursion + type() + dictionary comprehension + items() + loop
 
# helper function
def helper_fnc(ele, K):
    if type(ele) is list:
        return [helper_fnc(val, K) for val in ele]
    elif type(ele) is dict:
        return {key : helper_fnc(val, K) for key, val in ele.items()}
    return K
 
# initializing dictionary
test_dict = {'gfg' : [4, 6, 7], 'is' : 8, 'best' : [[4, 5], [8, 9, 20]]}
 
# printing original dictionary
print("The original dictionary : " + str(test_dict))
 
# initializing K
K = 4
 
# Reinitialize Value lists to K in Dictionary
# Using recursion + type() + dictionary comprehension + items() + loop
res = helper_fnc(test_dict, K)
     
# printing result
print("The Reinitialized dictionary : " + str(dict(res)))
Output : 

The original dictionary : {‘best’: [[4, 5], [8, 9, 20]], ‘is’: 8, ‘gfg’: [4, 6, 7]} 
The Reinitialized dictionary : {‘best’: [[4, 4], [4, 4, 4]], ‘is’: 4, ‘gfg’: [4, 4, 4]} 

 

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