How do I split Python list into equally-sized chunks?

Better Stack Team

Updated on January 26, 2023

To split a list into equally sized chunks, you can use the grouper function from the itertools module.

Here's an example of how you can use it:

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from itertools import zip_longest

def grouper(iterable, n, fillvalue=None):
    "Collect data into fixed-length chunks or blocks"
    # grouper('ABCDEFG', 3, 'x') --> ABC DEF Gxx
    args = [iter(iterable)] * n
    return zip_longest(*args, fillvalue=fillvalue)

# Example usage
my_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
n = 3
chunks = list(grouper(my_list, n))

print(chunks)

This will output the following list of chunks:

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[(1, 2, 3), (4, 5, 6), (7, 8, 9), (10, None, None)]

You can also use list slicing to achieve the same result:

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def split_list(my_list, chunk_size):
    return [my_list[i:i + chunk_size] for i in range(0, len(my_list), chunk_size)]

# Example usage
my_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
chunk_size = 3
chunks = split_list(my_list, chunk_size)

print(chunks)

This will output the following list of chunks:

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