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Python | Ways to shuffle a list
• Last Updated : 28 Nov, 2018

Shuffling a sequence of numbers have always been an useful utility and the question that has appeared in many company placement interviews as well. Knowing more than one method to achieve this can always be a plus. Let’s discuss certain ways in which this can be achieved.

Method #1 : Fisher–Yates shuffle Algorithm

This is one of the famous algorithms that is mainly employed to shuffle a sequence of numbers in python. This algorithm just takes the higher index value, and swaps it with current value, this process repeats in a loop till end of the list.

 `# Python3 code to demonstrate ``# shuffle a list ``# using Fisher–Yates shuffle Algorithm`` ` `import` `random`` ` `# initializing list ``test_list ``=` `[``1``, ``4``, ``5``, ``6``, ``3``]`` ` `# Printing original list ``print` `(``"The original list is : "` `+` `str``(test_list))`` ` `# using Fisher–Yates shuffle Algorithm``# to shuffle a list``for` `i ``in` `range``(``len``(test_list)``-``1``, ``0``, ``-``1``):``     ` `    ``# Pick a random index from 0 to i ``    ``j ``=` `random.randint(``0``, i ``+` `1``) ``   ` `    ``# Swap arr[i] with the element at random index ``    ``test_list[i], test_list[j] ``=` `test_list[j], test_list[i] ``     ` `# Printing shuffled list ``print` `(``"The shuffled list is : "` `+`  `str``(test_list))`
Output:
```The original list is : [1, 4, 5, 6, 3]
The shuffled list is : [4, 3, 1, 5, 6]
```

Method #2 : Using `random.shuffle()`
This is most recommended method to shuffle a list. Python in its random library provides this inbuilt function which in-place shuffles the list. Drawback of this is that list ordering is lost in this process. Useful for developers who choose to save time and hustle.

 `# Python3 code to demonstrate ``# shuffle a list ``# using random.shuffle()`` ` `import` `random`` ` `# initializing list ``test_list ``=` `[``1``, ``4``, ``5``, ``6``, ``3``]`` ` `# Printing original list ``print` `(``"The original list is : "` `+` `str``(test_list))`` ` `# using random.shuffle()``# to shuffle a list``random.shuffle(test_list)`` ` `# Printing shuffled list ``print` `(``"The shuffled list is : "` `+`  `str``(test_list))`
Output:
```The original list is : [1, 4, 5, 6, 3]
The shuffled list is : [5, 6, 4, 3, 1]
```

Method #3 : Using `random.sample()`
This is quite a useful function, better than the shuffle method used above in aspect that it creates a new shuffled list and returns it rather than disturbing the order of original list. This is useful in cases we require to retain the original list.

 `# Python3 code to demonstrate ``# shuffle a list ``# using random.sample()`` ` `import` `random`` ` `# initializing list ``test_list ``=` `[``1``, ``4``, ``5``, ``6``, ``3``]`` ` `# Printing original list ``print` `(``"The original list is : "` `+` `str``(test_list))`` ` `# using random.sample()``# to shuffle a list``res ``=` `random.sample(test_list, ``len``(test_list))`` ` `# Printing shuffled list ``print` `(``"The shuffled list is : "` `+`  `str``(res))`
Output:
```The original list is : [1, 4, 5, 6, 3]
The shuffled list is : [5, 3, 6, 1, 4]
```

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