Python | Ways to change keys in dictionary

Given a dictionary, the task is to change the key based on the requirement. Let’s see different methods we can do this task in Python.

Example:

initial dictionary:  {'nikhil': 1, 'manjeet': 10, 'Amit': 15}
final dictionary:    {'nikhil': 1, 'manjeet': 10, 'Suraj': 15}
c: Amit name changed to Suraj.

Method 1: Rename a Key in a Python Dictionary using the naive method 

Here, we used the native method to assign the old key value to the new one.

Output

initial 1st dictionary {'nikhil': 1, 'vashu': 5, 'manjeet': 10, 'akshat': 15}
final dictionary {'nikhil': 1, 'vashu': 5, 'manjeet': 10, 'akash': 15}

Time complexity: O(n), where n is the number of key-value pairs in the dictionary.
Auxiliary space: O(n), to store the keys and values in dictionary.

 Method 2: Rename a Key in a Python Dictionary using Python pop() 

We use the pop method to change the key value name.

Output

initial 1st dictionary {'nikhil': 1, 'vashu': 5, 'manjeet': 10, 'akshat': 15}
final dictionary {'nikhil': 1, 'vashu': 5, 'manjeet': 10, 'akash': 15}

 Method 3: Rename a Key in a Python Dictionary using Python zip() 

Suppose we want to change all keys of the dictionary.

Output

initial 1st dictionary {'nikhil': 1, 'vashu': 5, 'manjeet': 10, 'akshat': 15}
final dictionary {'a': 1, 'b': 5, 'c': 10, 'd': 15}

Creating a new dictionary and deleting the old one:

Approach:

Create a new empty dictionary new_dict.
Loop through each key-value pair in the original dictionary using the items() method.
If the current key is “Amit”, add a new key-value pair to new_dict with the key “Suraj” and the value from the original dictionary.
If the current key is not “Amit”, add the key-value pair from the original dictionary to new_dict.
Delete the old dictionary and rename new_dict to the original dictionary’s name.

{'nikhil': 1, 'manjeet': 10, 'Suraj': 15}

Time Complexity: O(n)
Auxiliary Space: O(n)