Python | List value merge in dictionary

Sometimes, while working with dictionaries, we can have a problem in which we have many dictionaries and we are required to merge like keys. This problem seems common, but complex is if the values of keys are list and we need to add elements to list of like keys. Let’s discuss way in which this problem can be solved.

Method : Using list comprehension + items()
This problem can be solved using list comprehension that can be used to merge the list content and also the items method which can be employed to get the dictionary keys and values.

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python3 code to demonstrate working of
# List value merge in dictionary
# Using items() + list comprehension
  
# initializing dictionaries
test_dict1 = {'Gfg' : [1, 2, 3], 'for' : [2, 4], 'CS' : [7, 8]}
test_dict2 = {'Gfg' : [10, 11], 'for' : [5], 'CS' : [0, 18]}
  
# printing original dictionaries
print("The original dictionary 1 is : " + str(test_dict1))
print("The original dictionary 2 is : " + str(test_dict2))
  
# Using items() + list comprehension
# List value merge in dictionary
res = {key: value + test_dict2[key] for key, value in test_dict1.items()}
  
# printing result 
print("The merged dictionary is : " + str(res))

chevron_right


Output :



The original dictionary 1 is : {‘for’: [2, 4], ‘CS’: [7, 8], ‘Gfg’: [1, 2, 3]}
The original dictionary 2 is : {‘for’: [5], ‘CS’: [0, 18], ‘Gfg’: [10, 11]}
The merged dictionary is : {‘for’: [2, 4, 5], ‘CS’: [7, 8, 0, 18], ‘Gfg’: [1, 2, 3, 10, 11]}



My Personal Notes arrow_drop_up

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.