Distribute an integer amount by a set of slots as evenly as possible

Question

I am trying to figure an elegant way of implementing the distribution of an amount into a given set of slots in python.

For example:

7 oranges distributed onto 4

Answer 1

Conceptually, what you want to do is compute 7 // 4 = 1 and 7 % 4 = 3. This means that all the plates get 1 whole orange. The remainder of 3 tells you that three of the plates get an extra orange.

The divmod builtin is a shortcut for getting both quantities simultaneously:

def distribute(oranges, plates):
    base, extra = divmod(oranges, plates)
    return [base + (i < extra) for i in range(plates)]

With your example:

>>> distribute(oranges=7, plates=4)
[2, 2, 2, 1]

For completeness, you'd probably want to check that oranges is non-negative and plates is positive. Given those conditions, here are some additional test cases:

>>> distribute(oranges=7, plates=1)
[7]

>>> distribute(oranges=0, plates=4)
[0, 0, 0, 0]

>>> distribute(oranges=20, plates=2)
[10, 10]

>>> distribute(oranges=19, plates=4)
[5, 5, 5, 4]

>>> distribute(oranges=10, plates=4)
[3, 3, 2, 2]