Sometimes, while working with Python dictionaries we can have a problem in which we need to perform a population of dictionary values using assigned variables after certain operation among them. This can have application in day-day programming. Let’s discuss certain ways in which this task can be performed.
Method #1 : Using lambda + dictionary comprehension
The combination of above functions can be used to solve this problem. In this, we perform the assignment using dictionary comprehension and values computations using lambda functions.
Python3
# Python3 code to demonstrate working of # Variable Operations Dictionary update# Using lambda + dictionary comprehension# helper functionshelper_fnc = {'Gfg': lambda: x + y, 'best': lambda: x * y}# initializing variablesx = 6y = 7# Variable Operations Dictionary update# Using lambda + dictionary comprehensionres = {key: val() for key, val in hlper_fnc.items()}# printing result print("The Initialized dictionary : " + str(res)) |
The Initialized dictionary : {'best': 42, 'Gfg': 13}
Time complexity: O(n), where n is the number of values in the dictionary.
Auxiliary Space: O(1), constant extra space is required
Method #2 : Using operators library
This task can also be performed using above functionality. In this, we use inbuilt operations provided by the operator library to achieve this task.
Python3
# Python3 code to demonstrate working of # Variable Operations Dictionary update# Using lambda + dictionary comprehensionfrom operator import add, mul# helper functionshelper_fnc = {'Gfg': add, 'best': mul}# initializing variablesx = 6y = 7# Variable Operations Dictionary update# Using lambda + dictionary comprehensionres = {'Gfg' : hlper_fnc['Gfg'](x, y), 'best' : hlper_fnc['best'](x, y)}# printing result print("The Initialized dictionary : " + str(res)) |
The Initialized dictionary : {'best': 42, 'Gfg': 13}
Method 3: Using the update() method:
Algorithm: This approach uses the update() method to merge the new_dict into the existing dictionary.
- Define the dict_update_method function, which takes in two dictionaries dictionary and new_dict.
- Use the update() method to merge the key-value pairs from new_dict into dictionary.
- Call the dict_update_method function with the two dictionaries to update dictionary with the key-value pairs from new_dict.
- Print out the dictionary before and after the update to verify the update was successful
Python3
def dict_update_method(dictionary, new_dict): dictionary.update(new_dict)example_input = {'a': 1, 'b': 2}new_dict = {'b': 3, 'c': 4}initialized_dict = {'best': 42, 'Gfg': 13}print("Before update:", example_input)dict_update_method(example_input, new_dict)print("After update:", example_input)print("Initialized dictionary:", initialized_dict) |
Before update: {'a': 1, 'b': 2}
After update: {'a': 1, 'b': 3, 'c': 4}
Initialized dictionary: {'best': 42, 'Gfg': 13}
Time Complexity: O(n) – where n is the number of items in the new_dict.
Auxiliary Space: O(1) – constant space is required for storing the new_dict and the updated dictionary.
Method 4: Use a simple for loop
Python3
# Python3 code to demonstrate working of # Variable Operations Dictionary update# Using for loopfrom operator import add, mul# helper functionshelper_fnc = {'Gfg': add, 'best': mul}# initializing variablesx = 6y = 7# Variable Operations Dictionary update# Using for loopres = {}for key, func in helper_fnc.items(): res[key] = func(x, y)# printing result print("The Initialized dictionary : " + str(res)) |
The Initialized dictionary : {'Gfg': 13, 'best': 42}
Time complexity: O(n), where n is the number of key-value pairs in the helper_fnc dictionary.
Auxiliary space: O(n), where n is the number of key-value pairs in the helper_fnc dictionary, because we need to create a new dictionary res to store the results.
