How do I calculate a mean with python?

[MRAB]

On 17/09/2013 00:33, William Bryant wrote:
> Hey I am new to python so go easy, but I wanted to know how to make a program that calculates the maen.
>
> List = [15, 6, 6, 7, 8, 9, 40]
> def mean():
>      global themean, thesum

You're iterating through every number in the list...

>      for i in List:

counting how many times each number occurs in the list:

>          thecount = List.count(i)

This line calculates the sum of the numbers on every iteration:

>          thesum = sum(List)

This line divides the sum of the numbers by the last count:

>      themean = thesum / thecount
>
> Why doesn't this work?
>
It does work; it just doesn't calculate the mean!

What you end up with is:

themean = sum(List) / List.count(40)

What you _really_ want is the sum of the numbers divided by the
number of numbers (i.e. the length of the list).