Python | Even values update in dictionary

Sometimes, while working with dictionaries, we might come across a problem in which we require to perform a particular operation on even value of keys. This type of problem can occur in web development domain. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using loop
This is the naive method in which this task can be performed. In this we simply run a loop to traverse each key and check for even in dictionary and perform the desired operation.

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python3 code to demonstrate working of
# Even values update in dictionary
# Using loop
  
# Initialize dictionary
test_dict = {'gfg' : 6, 'is' : 4, 'best' : 7}
  
# printing original dictionary
print("The original dictionary : " + str(test_dict))
  
# Using loop
# Even values update in dictionary
for key in test_dict: 
    if test_dict[key] % 2 == 0:
        test_dict[key] *= 3
  
# printing result 
print("The dictionary after triple even key's value : " + str(test_dict))

chevron_right






                        filter_none









Output :          




The original dictionary : {'best': 7, 'is': 4, 'gfg': 6}
The dictionary after triple even key's value : {'best': 7, 'is': 12, 'gfg': 18}





 


Method #2 : Using update() + dictionary comprehension

An alternate one-liner to perform this task, the combination of above functions can be used to perform this particular task. The update function is used to perform the necessary operation over the dictionary.











                                    filter_none




                                    edit

                                    close




                                    play_arrow




                                    link

                                    brightness_4

                                    code
                                




















# Python3 code to demonstrate working of 


# Even values update in dictionary 


# Using update() + dictionary comprehension 


  


# Initialize dictionary 


test_dict = {'gfg' : 6, 'is' : 4, 'best' : 7} 


  


# printing original dictionary 


print("The original dictionary : " + str(test_dict)) 


  


# Using update() + dictionary comprehension 


# Even values update in dictionary 


test_dict.update((x, y * 3) for x, y in test_dict.items() if y % 2 == 0) 


  


# printing result  


print("The dictionary after triple even key's value : " + str(test_dict)) 



















                        chevron_right







                        filter_none









Output :          


The original dictionary : {'best': 7, 'is': 4, 'gfg': 6}
The dictionary after triple even key's value : {'best': 7, 'is': 12, 'gfg': 18}








    

        My Personal Notes
        arrow_drop_up
    

    

        
        

            
            
        

    


Recommended Posts:
manjeet_04
Check out this Author's contributed articles.
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on  the "Improve Article" button below.