Python program to randomly create N Lists of K size

Given a List, the task is to write a Python program to randomly generate N lists of size K.

Examples:

Input : test_list = [6, 9, 1, 8, 4, 7], K, N = 3, 4

Output : [[8, 7, 6], [8, 6, 9], [8, 1, 6], [7, 8, 9]]

Explanation : 4 rows of 3 length are randomly extracted.

Input : test_list = [6, 9, 1, 8, 4, 7], K, N = 2, 3

Output : [[7, 6], [7, 9], [1, 9]]

Explanation : 3 rows of 2 length are randomly extracted.

Method 1 : Using generator + shuffle()

In this, getting random elements is done using shuffle(), and yield with slicing is used to get K size of shuffled list.

Output:

The original list is : [6, 9, 1, 8, 4, 7]
K sized N random lists : [[7, 1, 8], [8, 6, 1], [4, 9, 6], [6, 9, 1]]

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

Method 2 : Using product() + sample()

In this, all the possible permutations of K elements are extracted using product(), and from that random sampling of N lists are done.

Output:

The original list is : [6, 9, 1, 8, 4, 7]
K sized N random lists : [[1, 1, 1], [6, 9, 4], [8, 7, 6], [4, 8, 8]]

Time Complexity: O(n) where n is the number of elements in the list “test_list”. The product() + sample() is used to perform the task and it takes O(n) time.
Auxiliary Space: O(n), new list of size O(n) is created where n is the number of elements in the list 

Method 3: Using combinations() and randint()

We can use the combinations() function from the itertools module to generate all possible combinations of K elements from the input list, and then use the randint() function from the random module to select N random combinations.

 steps to implement this approach:

1. Import the required modules:
2. Define the function to generate K sized N random lists:
3. Call the function with the input list, K and N:

K sized N random lists : [(9, 1, 8), (6, 8, 7), (6, 9, 4), (1, 8, 4)]

Time complexity: O(1)
Auxiliary space: O(N)

Method 5: Using random.sample() and slicing

1. Import random module to use random.sample() method.
2. Initialize the list of integers test_list.
3. Initialize variables K and N.
4. Print the original list.
5. Use random.sample() method to get a random sample of K integers from test_list.
6. Repeat the above step N times using a loop and append the result to a list.
7. Print the final result.

The original list is : [6, 9, 1, 8, 4, 7]
K sized N random lists : [[4, 6, 8], [1, 7, 4], [6, 9, 1], [1, 8, 7]]

Time Complexity: O(NK)
Auxiliary Space: O(NK)

Method 6: Using NumPy library

The original list is : [6, 9, 1, 8, 4, 7]
K sized N random lists : [[4, 6, 8], [1, 7, 4], [6, 9, 1], [1, 8, 7]]

Time Complexity: O(N * K) since we still shuffle the array once and take the first N * K elements.
Auxiliary Space: O(N * K) as we need to store the shuffled array and the N subarrays.