TheAlgorithms/Python · error · ValueError

partitions must be a positive number!

Error message

partitions must be a positive number!

What it means

Raised by allocation_num in maths/allocation_number.py when the partitions argument is zero or negative. The function splits a byte range into 'partitions' contiguous chunks; a non-positive partition count makes the loop and the floor division undefined, so it is rejected first (before the partitions > number_of_bytes check).

Source

Thrown at maths/allocation_number.py:33

    :param number_of_bytes: the total of bytes.
    :param partitions: the number of partition need to be allocated.
    :return: list of bytes to be assigned to each worker thread

    >>> allocation_num(16647, 4)
    ['1-4161', '4162-8322', '8323-12483', '12484-16647']
    >>> allocation_num(50000, 5)
    ['1-10000', '10001-20000', '20001-30000', '30001-40000', '40001-50000']
    >>> allocation_num(888, 999)
    Traceback (most recent call last):
        ...
    ValueError: partitions can not > number_of_bytes!
    >>> allocation_num(888, -4)
    Traceback (most recent call last):
        ...
    ValueError: partitions must be a positive number!
    """
    if partitions <= 0:
        raise ValueError("partitions must be a positive number!")
    if partitions > number_of_bytes:
        raise ValueError("partitions can not > number_of_bytes!")
    bytes_per_partition = number_of_bytes // partitions
    allocation_list = []
    for i in range(partitions):
        start_bytes = i * bytes_per_partition + 1
        end_bytes = (
            number_of_bytes if i == partitions - 1 else (i + 1) * bytes_per_partition
        )
        allocation_list.append(f"{start_bytes}-{end_bytes}")
    return allocation_list


if __name__ == "__main__":
    import doctest

    doctest.testmod()

View on GitHub (pinned to f5988cc097)

Solutions

1. Validate partitions >= 1 at the call site before invoking allocation_num.
2. If partitions is derived (e.g. total // chunk_size), clamp with max(1, ...) or guard chunk_size > total.
3. Validate and cast config values to positive ints when loading.

Example fix

# before
parts = allocation_num(total, total // chunk_size)  # chunk_size > total -> 0

# after
partitions = max(1, total // chunk_size) if chunk_size <= total else 1
parts = allocation_num(total, partitions)

partitions = int(partitions)
if partitions < 1:
    raise ValueError(f'partitions must be >= 1, got {partitions}')
ranges = allocation_num(number_of_bytes, partitions)

When it happens

Trigger: Calling allocation_num(888, -4) or allocation_num(50000, 0). Non-integer partitions like 2.5 would not raise here but produce wrong chunking (range() over a float raises TypeError).

Common situations: User-supplied split counts from CLI/config parsed as 0 or negative, computed partition counts like number_of_bytes // chunk_size underflowing to 0 for tiny inputs, or defaults left unset.

Related errors

• partitions can not > number_of_bytes!
• Limit for the Catalan sequence must be ≥ 0
• Number should not be negative.
• Negative arguments are not supported
• the value of input must be a natural number

AI-assisted analysis of TheAlgorithms/Python@f5988cc097 (2026-08-14). Data as JSON: /api/errors/7d91eb9c9c44b1fb. Report an issue: GitHub.