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# Python | Check if k occurs atleast n times in a list

• Last Updated : 20 Feb, 2019

There are many common problems that a developer or common programmer comes across in day-day coding. One such problem is finding if an element occurs more than a certain number of times in the list. Let’s discuss certain ways to deal with this problem.

Method #1 : Using `sum()` + list comprehension
The list comprehension can be clubbed with the sum function for achieving this particular task. The sum function does the summation part and the logical case of returning true is dealt in list comprehension part.

 `# Python3 code to demonstrate ``# check for minimum N occureneces of K ``# using sum() + list comprehension`` ` `# initializing list``test_list ``=` `[``1``, ``3``, ``5``, ``5``, ``4``, ``5``]`` ` `# printing original list``print` `(``"The original list is : "` `+` `str``(test_list))`` ` `# initializing k ``k ``=` `5`` ` `# initializing N``N ``=` `3`` ` `# using sum() + list comprehension``# checking occurrences of K atleast N times ``res ``=` `0``res ``=` `sum``([``1` `for` `i ``in` `test_list ``if` `i ``=``=` `k]) >``=` `N``if` `res ``=``=` `1` `:``    ``res ``=` `True``else` `: ``    ``res ``=` `False``     ` `# printing result ``print` `(``"Does %d occur atleast %d times ? :"` `%``(k, N) ``+` `str``(res))`
Output:
```The original list is : [1, 3, 5, 5, 4, 5]
Does 5 occur atleast 3 times ? : True
```

Method #2 : Using `next() + islice()`
These both functions can be used together to perform this particular task in more efficient manner than above. The `islice `function would handle the summation part and next function helps with iteration logic.

 `# Python3 code to demonstrate ``# check for minimum N occureneces of K ``# using next() + islice()``from` `itertools ``import` `islice`` ` `# initializing list``test_list ``=` `[``1``, ``3``, ``5``, ``5``, ``4``, ``5``]`` ` `# printing original list``print` `(``"The original list is : "` `+` `str``(test_list))`` ` `# initializing k ``k ``=` `5`` ` `# initializing N``N ``=` `3`` ` `# using next() + islice()``# checking occurrences of K atleast N times ``func ``=` `(``True` `for` `i ``in` `test_list ``if` `i ``=``=` `k)``res ``=` `next``(islice(func, N``-``1``, ``None``), ``False``)``     ` `# printing result ``print` `(``"Does %d occur atleast %d times ? :"` `%``(k, N) ``+` `str``(res))`
Output:
```The original list is : [1, 3, 5, 5, 4, 5]
Does 5 occur atleast 3 times ? : True
```

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