Chunk a list into n-sized parts

Split any list into consecutive chunks of a fixed size.

list chunking slicing

Write a function `chunk_list(items, n)` that takes a list `items` and a positive integer `n`, and returns a new list of sublists, each containing up to `n` elements, preserving the original order. The last chunk may have fewer than `n` elements. If `items` is empty, return an empty list. If `n` is not positive, raise a `ValueError`.

Constraints

0 <= len(items) <= 100000
n >= 1 (must raise ValueError if n < 1)
The chunks must be in order.

Example

>>> chunk_list([1,2,3,4,5], 2)
[[1,2], [3,4], [5]]
>>> chunk_list(['a','b','c'], 3)
[['a','b','c']]
>>> chunk_list([], 5)
[]

10 points ~15 min

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Hints

Use a loop with range(start, len(items), n).

Slicing items[i:i+n] gives the next chunk.

Check n < 1 at the beginning and raise ValueError('n must be positive').

The result should be a list of lists, not a list of tuples.

Test Results

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