Reference library

Comprehensions & generators

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

5 matches

Cycle an iterable forever in Python

Define a generator that repeatedly yields items from an iterable, cycling back to the beginning infinitely.

def cycle_generator(iterable):
    """Yield items from iterable forever, cycling back to the start."""
    items = list(iterable)  # Convert to list so it can restart
    index = 0
    while True:
        yield items[index]
        index = (index + 1) % len(items)


if __name__ == "__main__":
    colors = ["red", "gre…

14 0 Open

Comprehensions & generators easy

Generator Function to Yield an Infinite Counter in Python

This code demonstrates a generator function that yields an infinite sequence of integers starting from a given value, allowing lazy, memory-efficient iteration.

generators infinite sequences yield

Python

def infinite_counter(start=0):
    count = start
    while True:
        yield count
        count += 1

if __name__ == "__main__":
    counter = infinite_counter(5)
    for _ in range(5):
        print(next(counter))

14 0 Open

Comprehensions & generators easy

How to Create an Infinite Arithmetic Sequence Generator in Python

Build a memory-efficient generator that yields an infinite arithmetic progression and extract the first N values with list comprehension.

generators yield infinite-sequences

Python

"""Count generator infinite arithmetic progression"""


def arithmetic_counter(start=0, step=1):
    """Generate an infinite arithmetic sequence."""
    current = start
    while True:
        yield current
        current += step


if __name__ == "__main__":
    counter = arithmetic_counter(1, 3)
    result = [next(c…

14 0 Open

Comprehensions & generators easy

How to Generate Fibonacci Numbers in Python Without Recursion

Build an efficient infinite Fibonacci sequence using a generator function with O(1) memory and no recursion overhead.

generators fibonacci iteration

Python

def fib(n):
    a, b = 0, 1
    for _ in range(n):
        yield a
        a, b = b, a + b

if __name__ == "__main__":
    count = 10
    result = list(fib(count))
    print(result)

15 0 Open

Comprehensions & generators easy

Take n items from an infinite Python generator

Uses itertools.islice to lazily take exactly n items from an infinite generator without exhausting it.

generators itertools islice

Python

from itertools import islice

def count_up_from(start=0):
    n = start
    while True:
        yield n
        n += 1

def take_n(generator, count):
    return list(islice(generator, count))

if __name__ == "__main__":
    gen = count_up_from(10)
    result = take_n(gen, 5)
    print(result)

11 0 Open

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