# Python – Count frequency of Sublist in given list

Given a List and a sublist, count occurrence of sublist in list.

Input : test_list = [4, 5, 3, 5, 7, 8, 3, 5, 7, 2, 3, 5, 7], sublist = [3, 5, 7]
Output : 3
Explanation : 3, 5, 7 occurs 3 times.

Input : test_list = [4, 5, 3, 5, 8, 8, 3, 2, 7, 2, 3, 6, 7], sublist = [3, 5, 7]
Output : 0
Explanation : No occurrence found.

Method #1 : Using list comprehension + slicing

In this, we test for each sublist of list extracted using slicing, if found, the element is added to list, at last length of list is computed using len().

## Python3

 `# Python3 code to demonstrate working of  ` `# Sublist Frequency ` `# Using list comprehension + slicing  ` ` `  `# initializing list ` `test_list ``=` `[``4``, ``5``, ``3``, ``5``, ``7``, ``8``, ``3``, ``5``, ``7``, ``2``, ``7``, ``3``, ``2``] ` ` `  `# printing original list ` `print``(``"The original list is : "` `+` `str``(test_list)) ` ` `  `# initializing Sublist ` `sublist ``=` `[``3``, ``5``, ``7``] ` ` `  `# slicing is used to extract chunks and compare ` `res ``=` `len``([sublist ``for` `idx ``in` `range``(``len``(test_list)) ``if` `test_list[idx : idx ``+` `len``(sublist)] ``=``=` `sublist]) ` ` `  `# printing result  ` `print``(``"The sublist count : "` `+` `str``(res)) `

Output

```The original list is : [4, 5, 3, 5, 7, 8, 3, 5, 7, 2, 7, 3, 2]
The sublist count : 2
```

Method #2 : Using zip_longest() + islice() + all() + loop

In this, we perform task of slicing using islice() and check if each element is matching using all(), zip_longest() helps in mapping elements to check for equality from sublist. Loop is used to get to index match with first element of sublist in list, to make it more efficient.

## Python3

 `# Python3 code to demonstrate working of  ` `# Sublist Frequency ` `# Using zip_longest() + islice() + all() + loop  ` `from` `itertools ``import` `zip_longest, islice ` ` `  `# initializing list ` `test_list ``=` `[``4``, ``5``, ``3``, ``5``, ``7``, ``8``, ``3``, ``5``, ``7``, ``2``, ``7``, ``3``, ``2``] ` ` `  `# printing original list ` `print``(``"The original list is : "` `+` `str``(test_list)) ` ` `  `# initializing Sublist ` `sublist ``=` `[``3``, ``5``, ``7``] ` ` `  `# slicing is used to extract chunks and compare ` `res ``=` `[] ` `idx ``=` `0`   `while` `True``: ` `    ``try``: ` `         `  `        ``# getting to the index ` `        ``idx ``=` `test_list.index(sublist[``0``], idx) ` `    ``except` `ValueError: ` `        ``break` `     `  `    ``# using all() to check for all elements equivalence ` `    ``if` `all``(x ``=``=` `y ``for` `(x, y) ``in` `zip_longest(sublist, islice(test_list, idx, idx ``+` `len``(sublist)))): ` `        ``res.append(sublist) ` `        ``idx ``+``=` `len``(sublist) ` `    ``idx ``+``=` `1` ` `  `res ``=` `len``(res) ` ` `  `# printing result  ` `print``(``"The sublist count : "` `+` `str``(res)) `

Output

```The original list is : [4, 5, 3, 5, 7, 8, 3, 5, 7, 2, 7, 3, 2]
The sublist count : 2
```

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