Python | Shuffle two lists with same order
Sometimes, while working with Python list, we can have a problem in which we need to perform shuffle operation in list. This task is easy and there are straightforward functionalities available in Python to perform this. But sometimes, we need to shuffle two lists so that their shuffle orders are consistent. Let’s discuss a way in which this task can be performed.
Method : Using zip() + shuffle() + * operator
In this method, this task is performed in three steps. Firstly, the lists are zipped together using zip(). Next step is to perform shuffle using inbuilt shuffle() and last step is to unzip the lists to separate lists using * operator.
The original list 1 : [6, 4, 8, 9, 10] The original list 2 : [1, 2, 3, 4, 5] List 1 after shuffle : [6, 10, 4, 8, 9] List 2 after shuffle : [1, 5, 2, 3, 4]
Time Complexity: O(n*n) where n is the number of elements in the list “test_list”. zip() + shuffle() + * operator performs n*n number of operations.
Auxiliary Space: O(n*n), extra space is required where n is the number of elements in the list
Method #2: using random + zip()
We are using the zip() function to combine the two lists into a list of tuples, which is then shuffled using random.shuffle(). Finally, we are using zip() again to separate the shuffled tuples into two separate lists.
1. Create two original lists: list1 and list2
2. Combine the two lists using the zip() function and store the result in a variable called zipped
3. Shuffle the zipped list using the random.shuffle() function
4. Unzip the shuffled list back into two separate lists using zip() and store the result in list1 and list2 variables
5. Print the shuffled lists
List 1 after shuffle: (4, 9, 10, 6, 8) List 2 after shuffle: (2, 4, 5, 1, 3)
Time complexity: O(NlogN) where N is the length of the input lists. This is because the zip() function takes O(N) time, random.shuffle() takes O(N) time, and zip() again takes O(N) time. The dominant factor is the random.shuffle() function which has a time complexity of O(NlogN).
Auxiliary Space: O(N) as we are creating a new list of tuples using zip(), which has a length of N.
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