Python – Cross mapping of Two dictionary value lists

GIven two dictionaries with list values, perform mapping of keys of first list with values of other list, by checking values-key linkage.

Input : test_dict1 = {“Gfg” : [4, 10], “Best” : [8, 6], “is” : [9, 3]}, test_dict2 = {6 : [15, 9], 8 : [6, 3], 7 : [9, 8], 9 : [10, 11]}
Output : {‘Best’: [6, 3, 15, 9], ‘is’: [10, 11]}
Explanation : “Best” has 8 and 6, which are mapped to 6, 3 and 15, 9 hence output for that key.

Input : test_dict1 = {“Gfg” : [4, 10], “Best” : [18, 16], “is” : [9, 3]}, test_dict2 = {6 : [15, 9], 8 : [6, 3], 7 : [9, 8], 9 : [10, 11]}
Output : {‘is’: [10, 11]}
Explanation : Only 9 present as possible key.

Method #1 : Using loop + setdefault() + extend()

The combination of above functions can be used to solve this problem. In this, we perform the task of getting the matching keys with values using get() and setdefault is used to construct empty list for mapping.



Python3

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python3 code to demonstrate working of 
# Cross mapping of Two dictionary value lists
# Using loop + setdefault() + extend()
  
# initializing dictionaries
test_dict1 = {"Gfg" : [4, 7], "Best" : [8, 6], "is" : [9, 3]}
test_dict2 = {6 : [15, 9], 8 : [6, 3], 7 : [9, 8], 9 : [10, 11]}
  
# printing original lists
print("The original dictionary 1 is : " + str(test_dict1))
print("The original dictionary 2 is : " + str(test_dict2))
  
res = {}
  
# getting all values of first dictionary 
for key, val in test_dict1.items():
    for key1 in val:
          
        # getting result with default value list and extending 
        # according to value optained from get()
        res.setdefault(key, []).extend(test_dict2.get(key1, []))
  
# printing result 
print("The constructed dictionary : " + str(res)) 

chevron_right


Output

The original dictionary 1 is : {'Gfg': [4, 7], 'Best': [8, 6], 'is': [9, 3]}
The original dictionary 2 is : {6: [15, 9], 8: [6, 3], 7: [9, 8], 9: [10, 11]}
The constructed dictionary : {'Gfg': [9, 8], 'Best': [6, 3, 15, 9], 'is': [10, 11]}

Method #2 : Using list comprehension + dictionary comprehension

This is one more way in which this problem can be solved. In this, we extract all the mapping using list comprehension and then contruct new dictionary by cross-mapping the extracted values.

Python3

filter_none

edit
close

play_arrow

link
brightness_4
code

# Python3 code to demonstrate working of 
# Cross mapping of Two dictionary value lists
# Using list comprehension + dictionary comprehension
  
# initializing dictionaries
test_dict1 = {"Gfg" : [4, 7], "Best" : [8, 6], "is" : [9, 3]}
test_dict2 = {6 : [15, 9], 8 : [6, 3], 7 : [9, 8], 9 : [10, 11]}
  
# printing original lists
print("The original dictionary 1 is : " + str(test_dict1))
print("The original dictionary 2 is : " + str(test_dict2))
  
# using internal and external comprehension to 
# solve problem 
res = {key: [j for i in val if i in test_dict2 for j in test_dict2[i]]
      for key, val in test_dict1.items()}
  
# printing result 
print("The constructed dictionary : " + str(res)) 

chevron_right


Output

The original dictionary 1 is : {'Gfg': [4, 7], 'Best': [8, 6], 'is': [9, 3]}
The original dictionary 2 is : {6: [15, 9], 8: [6, 3], 7: [9, 8], 9: [10, 11]}
The constructed dictionary : {'Gfg': [9, 8], 'Best': [6, 3, 15, 9], 'is': [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.