# Python – Retain records with N occurrences of K

• Last Updated : 02 Sep, 2021

Sometimes, while working with Python tuples list, we can have a problem in which we need to perform retention of all the records where occurrences of K is N times. This kind of problem can come in domains such as web development and day-day programming. Let’s discuss certain ways in which this task can be performed.

Input : test_list = [(4, 5, 5, 4), (5, 4, 3)], K = 5, N = 2
Output : [(4, 5, 5, 4)]
Input : test_list = [(4, 5, 5, 4), (5, 4, 3)], K = 5, N = 3
Output : []

Method #1 : Using list comprehension + count()
The combination of above functions can be used to solve this problem. In this, we perform the task of counting occurrences and conditions and iterations using list comprehension.

## Python3

 `# Python3 code to demonstrate working of ` `# Retain records with N occurrences of K` `# Using count() + list comprehension`   `# initializing list` `test_list ``=` `[(``4``, ``5``, ``6``, ``4``, ``4``), (``4``, ``4``, ``3``), (``4``, ``4``, ``4``), (``3``, ``4``, ``9``)]`   `# printing original list` `print``(``"The original list is : "` `+` `str``(test_list))`   `# initializing K` `K ``=` `4`   `# initializing N ` `N ``=` `3`   `# Retain records with N occurrences of K` `# Using count() + list comprehension` `res ``=` `[ele ``for` `ele ``in` `test_list ``if` `ele.count(K) ``=``=` `N]`   `# printing result ` `print``(``"Filtered tuples : "` `+` `str``(res)) `

Output :

```The original list is : [(4, 5, 6, 4, 4), (4, 4, 3), (4, 4, 4), (3, 4, 9)]
Filtered tuples : [(4, 5, 6, 4, 4), (4, 4, 4)]```

Method #2 : Using list comprehension + sum()
The combination of above functions can be used to solve this problem. In this, we perform the task of computing summation count of K using sum().

## Python3

 `# Python3 code to demonstrate working of ` `# Retain records with N occurrences of K` `# Using list comprehension + sum()`   `# initializing list` `test_list ``=` `[(``4``, ``5``, ``6``, ``4``, ``4``), (``4``, ``4``, ``3``), (``4``, ``4``, ``4``), (``3``, ``4``, ``9``)]`   `# printing original list` `print``(``"The original list is : "` `+` `str``(test_list))`   `# initializing K` `K ``=` `4`   `# initializing N ` `N ``=` `3`   `# Retain records with N occurrences of K` `# Using list comprehension + sum()` `res ``=` `[ele ``for` `ele ``in` `test_list ``if` `sum``(cnt ``=``=` `K ``for` `cnt ``in` `ele) ``=``=` `N]`   `# printing result ` `print``(``"Filtered tuples : "` `+` `str``(res)) `

Output :

```The original list is : [(4, 5, 6, 4, 4), (4, 4, 3), (4, 4, 4), (3, 4, 9)]
Filtered tuples : [(4, 5, 6, 4, 4), (4, 4, 4)]```

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