Improving readability

Coders sometimes don't see the point in writing a function with a body of one or two lines of code, so let's look at an example that shows you why you should do it.

Imagine that you need to multiply two matrices:

Would you prefer to have to read this code:

# matrix.multiplication.nofunc.py
a = [[1, 2], [3, 4]]
b = [[5, 1], [2, 1]]

c = [[sum(i * j for i, j in zip(r, c)) for c in zip(*b)]
     for r in a]

Or would you prefer this one:

# matrix.multiplication.func.py
# this function could also be defined in another module
def matrix_mul(a, b):
    return [[sum(i * j for i, j in zip(r, c)) for c in zip(*b)]
            for r in a]

a = [[1, 2], [3, 4]]
b = [[5, 1], [2, 1]]
c = matrix_mul(a, b)

It's much easier to understand that c is the result of the multiplication between a and b in the second example. It's much easier to read through the code and, if you don't need to modify that multiplication logic, you don't even need to go into the implementation details. Therefore, readability is improved here while, in the first snippet, you would have to spend time trying to understand what that complicated list comprehension is doing.