Problem 1.5

Mean

Write a function mean to compute the arthematic mean of a list of numbers.

The arthemetic mean of N numbers is computed by adding all the N numbers and dividing the total by N.

The function takes the list of numbers as argument and returns the mean.

>>> mean([1, 2, 3, 4, 5])
3.0

Solution

def mean(numbers):
    return sum(numbers)/len(numbers)

Discussion

The solution is quite straight-forward. We use the built-in function sum to compute the total and divide it by the number of numbers, which is computed using the built-in function len.

def mean(numbers):
    return sum(numbers) / len(numbers)

You could also write that in multiple lines, if you find that more comfortable.

def mean(numbers):
    total = sum(numbers)
    n = len(numbers)
    return total / n