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Python | Group list elements based on frequency
• Last Updated : 25 Jun, 2019

Given a list of elements, write a Python program to group list elements and their respective frequency within a tuple.

Examples:

```Input : [1, 3, 4, 4, 1, 5, 3, 1]
Output : [(1, 3), (3, 2), (4, 2), (5, 1)]

Input : ['x', 'a', 'x', 'y', 'a', 'x']
Output : [('x', 3), ('a', 2), ('y', 1)]
```

Method #1 : List comprehension

We can use list comprehension to form tuples of each element and the count of its occurrence and store it in ‘res’, but that will contain the duplicate first element. Thus, to remove the duplicate first element, we use `OrderedDict(res).items()`.

 `# Python3 program to Grouping list ``# elements based on frequency``from` `collections ``import` `OrderedDict `` ` `def` `group_list(lst):``     ` `    ``res ``=`  `[(el, lst.count(el)) ``for` `el ``in` `lst]``    ``return` `list``(OrderedDict(res).items())``     ` `# Driver code``lst ``=` `[``1``, ``3``, ``4``, ``4``, ``1``, ``5``, ``3``, ``1``]``print``(group_list(lst))`
Output:

```[(1, 3), (3, 2), (4, 2), (5, 1)]
```

Method #2 : Using `collections.Counter()`

`collections.Counter()` provides two direct methods `keys()` and `values()` that provides the elements and its occurrences. At last, zip them together using Python `zip()` method.

 `# Python3 program to Grouping list ``# elements based on frequency``from` `collections ``import` `Counter`` ` `def` `group_list(lst):``     ` `    ``return` `list``(``zip``(Counter(lst).keys(), Counter(lst).values()))``     ` `# Driver code``lst ``=` `[``1``, ``3``, ``4``, ``4``, ``1``, ``5``, ``3``, ``1``]``print``(group_list(lst))`
Output:
```[(1, 3), (3, 2), (4, 2), (5, 1)]
```

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