Reference library

Algorithms & data structures

Classic patterns — search, sort, stacks, queues, and practical complexity-aware code.

3 matches

Drop Elements From Start While Condition Is True in Python

This generator function drops elements from the beginning of an iterable while a predicate returns true, then yields the rest.

generator iteration filtering

Python

def drop_while(predicate, iterable):
    """Drop elements from the start while predicate is true."""
    it = iter(iterable)
    for item in it:
        if not predicate(item):
            yield item
            break
    yield from it

if __name__ == "__main__":
    numbers = [1, 2, 3, 4, 1, 2, 5]
    result = list(d…

12 0 Open

Algorithms & data structures easy

Find the First Index Where a Condition Is True in Python

Search any iterable for the first element matching a predicate and return its index, or -1 if none match.

search enumerate index

Python

def first_true_index(items, condition):
    """Return the first index where condition(item) is True, or -1 if none match."""
    for i, item in enumerate(items):
        if condition(item):
            return i
    return -1


if __name__ == "__main__":
    numbers = [1, 3, 5, 8, 10, 12]
    # Find first number greate…

12 0 Open

Algorithms & data structures easy

Take While Predicate True From Start in Python

Create a custom take_while function that collects elements from an iterable until a predicate returns False, then stops.

takewhile iteration predicate

Python

def take_while(predicate, iterable):
    """Return elements from iterable until the predicate becomes False."""
    result = []
    for item in iterable:
        if predicate(item):
            result.append(item)
        else:
            break
    return result


if __name__ == "__main__":
    numbers = [2, 4, 6, 7,…

13 0 Open

Browse by section

Each section groups closely related Python snippets.