Python: Randomize the order of the values of an list

Last update on December 21 2024 13:11:06 (UTC/GMT +8 hours)

Shuffle List Randomly

Write a Python program to randomize the order of the values of a list, returning a new list.

• Uses the Fisher-Yates algorithm to reorder the elements of the list.
• random.shuffle provides similar functionality to this snippet.

From Wikipedia,
The Fisher–Yates shuffle is an algorithm for generating a random permutation of a finite sequence—in plain terms, the algorithm shuffles the sequence. The algorithm effectively puts all the elements into a hat; it continually determines the next element by randomly drawing an element from the hat until no elements remain. The algorithm produces an unbiased permutation: every permutation is equally likely. The modern version of the algorithm is efficient: it takes time proportional to the number of items being shuffled and shuffles them in place.

Sample Solution:

Python Code:

# Import necessary modules.
from copy import deepcopy
from random import randint

# Define a function called 'shuffle_list' that takes a list 'lst' as an argument.
def shuffle_list(lst):
  # Create a deep copy of the input list to avoid modifying the original list.
  temp_lst = deepcopy(lst)
  # Get the length of the copied list.
  m = len(temp_lst)
  # Perform Fisher-Yates shuffle by iterating over the list and swapping elements randomly.
  while (m):
    m -= 1
    i = randint(0, m)
    temp_lst[m], temp_lst[i] = temp_lst[i], temp_lst[m]
  # Return the shuffled list.
  return temp_lst

# Example usage: Shuffle the elements of the list 'nums'.
nums = [1, 2, 3, 4, 5, 6]
print("Original list: ", nums)
print("\nShuffle the elements of the said list:")
print(shuffle_list(nums)) 

Sample Output:

Original list:  [1, 2, 3, 4, 5, 6]

Shuffle the elements of the said list:
[3, 2, 4, 1, 6, 5]

Flowchart:

Python Code Editor:

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