# Python | Sort list elements by frequency

Given a list containing repeated and non-repeated elements, the task is to sort the given list on basis of the frequency of elements. Let’s discuss few methods for same.

Method #1: Using `collections.counter()`

 `# Python code to demonstrate ` `# sort list by frequency ` `# of elements ` ` `  `from` `collections ``import` `Counter ` ` `  `ini_list ``=` `[``1``, ``2``, ``3``, ``4``, ``4``, ``5``, ``5``, ``5``, ``5``, ``7``,  ` `            ``1``, ``1``, ``2``, ``4``, ``7``, ``8``, ``9``, ``6``, ``6``, ``6``] ` ` `  `# printing initial ini_list ` `print` `(``"initial list"``, ``str``(ini_list)) ` ` `  `# sorting on bais of frequency of elements ` `result ``=` `[item ``for` `items, c ``in` `Counter(ini_list).most_common() ` `                                      ``for` `item ``in` `[items] ``*` `c] ` ` `  `# printing final result ` `print``(``"final list"``, ``str``(result)) `

Output:

initial list [1, 2, 3, 4, 4, 5, 5, 5, 5, 7, 1, 1, 2, 4, 7, 8, 9, 6, 6, 6]
final list [5, 5, 5, 5, 1, 1, 1, 4, 4, 4, 6, 6, 6, 2, 2, 7, 7, 3, 8, 9]

Method #2: Using iterables

 `# Python code to demonstrate ` `# sort list by frequency ` `# of elements ` ` `  `from` `collections ``import` `Counter ` `from` `itertools ``import` `repeat, chain ` ` `  `ini_list ``=` `[``1``, ``2``, ``3``, ``4``, ``4``, ``5``, ``5``, ``5``, ``5``, ``7``, ` `            ``1``, ``1``, ``2``, ``4``, ``7``, ``8``, ``9``, ``6``, ``6``, ``6``] ` ` `  `# printing initial ini_list ` `print` `(``"initial list"``, ``str``(ini_list)) ` ` `  `# sorting on bais of frequency of elements ` `result ``=` `list``(chain.from_iterable(repeat(i, c) ` `         ``for` `i, c ``in` `Counter(ini_list).most_common())) ` ` `  `# printing final result ` `print``(``"final list"``, ``str``(result)) `

Output:

initial list [1, 2, 3, 4, 4, 5, 5, 5, 5, 7, 1, 1, 2, 4, 7, 8, 9, 6, 6, 6]
final list [5, 5, 5, 5, 1, 1, 1, 4, 4, 4, 6, 6, 6, 2, 2, 7, 7, 3, 8, 9]

Method #3: Using sorted

 `# Python code to demonstrate ` `# sort list by frequency ` `# of elements ` ` `  `from` `collections ``import` `Counter ` ` `  `ini_list ``=` `[``1``, ``1``, ``2``, ``2``, ``2``, ``3``, ``3``, ``3``, ``3``, ``3``, ` `               ``5``, ``5``, ``5``, ``4``, ``4``, ``4``, ``4``, ``4``, ``4``] ` ` `  `# printing initial ini_list ` `print` `(``"initial list"``, ``str``(ini_list)) ` ` `  `# sorting on bais of frequency of elements ` `result ``=` `sorted``(ini_list, key ``=` `ini_list.count, ` `                                ``reverse ``=` `True``) ` ` `  `# printing final result ` `print``(``"final list"``, ``str``(result)) `

Output:

initial list [1, 1, 2, 2, 2, 3, 3, 3, 3, 3, 5, 5, 5, 4, 4, 4, 4, 4, 4]
final list [4, 4, 4, 4, 4, 4, 3, 3, 3, 3, 3, 2, 2, 2, 5, 5, 5, 1, 1]

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