How to Efficiently Iterate Over a List in Chunks in Python?

How to Iterate Over a List in Chunks

The need to iterate over a list in chunks arises in various programming scenarios, such as processing large datasets. This article delves into the most efficient and Pythonic ways to achieve this task.

Traditionally, a C-style approach using a range loop with explicit index manipulation was employed:

for i in range(0, len(ints), 4):
    # dummy op for example code
    foo += ints[i] * ints[i + 1] + ints[i + 2] * ints[i + 3]

While this method may be straightforward, it lacks Pythonic elegance.

A more Pythonic alternative was proposed:

while ints:
    foo += ints[0] * ints[1] + ints[2] * ints[3]
    ints[0:4] = []

This approach leverages Python's list slicing to remove the processed elements, presenting a cleaner solution.

Python 3.12's Introduction of chunker()

With the release of Python 3.12, the highly anticipated chunker() function was introduced:

from itertools import islice

def chunker(seq, size):
    it = iter(seq)
    while True:
        chunk = list(islice(it, size))
        if not chunk:
            break
        yield chunk

This function elegantly iterates over any type of sequence, splitting it into chunks of the desired size. The following examples illustrate its versatility:

text = "I am a very, very helpful text"

for group in chunker(text, 7):
    print(repr(group),)
# 'I am a ' 'very, v' 'ery hel' 'pful te' 'xt'

print('|'.join(chunker(text, 10)))
# I am a ver|y, very he|lpful text

animals = ['cat', 'dog', 'rabbit', 'duck', 'bird', 'cow', 'gnu', 'fish']

for group in chunker(animals, 3):
    print(group)
# ['cat', 'dog', 'rabbit']
# ['duck', 'bird', 'cow']
# ['gnu', 'fish']

The chunker() function enhances Python's already rich ecosystem of list manipulation and further exemplifies its user-friendliness.

The above is the detailed content of How to Efficiently Iterate Over a List in Chunks in Python?. For more information, please follow other related articles on the PHP Chinese website!