Python language basics 66: a practical example of a yield generator in Python

Introduction

In the previous post we continued our investigation of yield generators in Python. In particular we looked at how a yield function could remember the state of its internal variables. We saw how code execution jumps in and out of a yield function as it’s being enumerated.

At this point you may think that yield functions are interesting but what can they be used for? You’ll find a lot of examples on the internet. In this post we’ll look at the following scenario:

Say you’d like to divide an integer, e.g. 20, into equal parts of 3 and distribute any remainder equally across the groups. The result of such an operation would be the following 3 integers:

7,7,6

20 can be divided into 3 equal parts of 6 and we have a remainder of 20 – 6 * 3 = 2. 2 is then added as 1 and 1 to the first two groups of 6. The result is a more or less equal distribution of the start integer.

The following function will perform just that:

import math

def distribute_integer(total, divider):
    if divider == 0:
        yield 0
    else:
        rest = total % divider
        result = total / divider

        for i in range(0, divider):
            if rest > 0:
                rest -= 1
                yield math.ceil(result)
            else:
                yield math.floor(result)

groups = distribute_integer(20, 3)
for g in groups:
    print(g)

This will print 7,7,6 as expected.

Read the next part here.

Read all Python-related posts on this blog here.