Python - All combination Dictionary List

Given 2 lists, form all possible combination of dictionaries that can be formed by taking keys from list1 and values from list2.

Input : test_list1 = ["Gfg", "is", "Best"], test_list2 = [4] 
Output : [{'Gfg': 4, 'is': 4, 'Best': 4}]
Explanation : All combinations dictionary list extracted.
 

Input : test_list1 = ["Gfg", "is", "Best"], test_list2 = [5, 6] 
Output : [{'Gfg': 5, 'is': 5, 'Best': 5}, {'Gfg': 5, 'is': 5, 'Best': 6}, {'Gfg': 5, 'is': 6, 'Best': 5}, {'Gfg': 5, 'is': 6, 'Best': 6}, {'Gfg': 6, 'is': 5, 'Best': 5}, {'Gfg': 6, 'is': 5, 'Best': 6}, {'Gfg': 6, 'is': 6, 'Best': 5}, {'Gfg': 6, 'is': 6, 'Best': 6}] 
Explanation : All combinations dictionary list extracted. 
 

Method #1 : Using product() + dictionary comprehension + list comprehension

In this, we get all the combination possible using product() and dictionary comprehension generates each dictionary, list comprehension is used to iterate combinations generated.

Output:

The original list 1 is : ['Gfg', 'is', 'Best'] The original list 2 is : [4, 5] The combinations dictionary : [{'Gfg': 4, 'is': 4, 'Best': 4}, {'Gfg': 4, 'is': 4, 'Best': 5}, {'Gfg': 4, 'is': 5, 'Best': 4}, {'Gfg': 4, 'is': 5, 'Best': 5}, {'Gfg': 5, 'is': 4, 'Best': 4}, {'Gfg': 5, 'is': 4, 'Best': 5}, {'Gfg': 5, 'is': 5, 'Best': 4}, {'Gfg': 5, 'is': 5, 'Best': 5}]

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

Method #2 : Using permutations() + dictionary comprehension + list comprehension [ For unique elements ]

If we require values to be all unique, permutations() can be used inplace of product() to achieve this task.

Output:

The original list 1 is : ['Gfg', 'is', 'Best'] The original list 2 is : [4, 5, 6] The combinations dictionary : [{'Gfg': 4, 'is': 5, 'Best': 6}, {'Gfg': 4, 'is': 6, 'Best': 5}, {'Gfg': 5, 'is': 4, 'Best': 6}, {'Gfg': 5, 'is': 6, 'Best': 4}, {'Gfg': 6, 'is': 4, 'Best': 5}, {'Gfg': 6, 'is': 5, 'Best': 4}]

Time Complexity: O(n!) where n is the number of elements in the list “test_list”.  permutations() + dictionary comprehension + list comprehension performs n! number of operations.
Auxiliary Space: O(n), extra space of size n is required