Python: Split the list of integers into N sized chunks in one line

February 28, 2018

So you want to split the list of integers into smaller N-chunks (let's say 20)? In one line? ..okay, here is the code:

>>> list1 = [n for n in range(123)]
>>> sizes_of = 20
>>> n_sized_chunks = [list1[i:i+sizes_of] for i in range(0, len(list1), sizes_of)]
>>> n_sized_chunks
[[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19], [20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39], [40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59], [60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79], [80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96,97, 98, 99], [100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119], [120, 121, 122]]

Notice that, even though there are 123 items, we did't get the out of index error or any other nasty result. Instead we got 6 chunks of 20 plus one extra chunk of what has remained [120,121,122] Now if you want to know the sum of each sub-list/chunk, and you don't need the whole list, easy, just add sum() to listcomp like this:

>>> n_sized_chunks = [sum(list1[i:i+sizes_of]) for i in range(0, len(list1), sizes_of)]
>>> n_sized_chunks

[190, 590, 990, 1390, 1790, 2190, 363]