Reference library

Comprehensions & generators

List/dict/set comprehensions, generator expressions, and lazy iteration.

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Comprehensions & generators easy

How to Slice a Generator with islice in Python

Use itertools.islice to take the first n items from any iterable without materializing the whole sequence into a list.

itertools islice generators
Python 
from itertools import islice


def first_n(iterable, n):
    """Return the first n items from an iterable."""
    return list(islice(iterable, n))


if __name__ == "__main__":
    numbers = range(10, 100)  # large iterable
    result = first_n(numbers, 5)
    print(result)  # [10, 11, 12, 13, 14]
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