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Re: How do I calculate a mean with python?

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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).

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Thread

How do I calculate a mean with python? William Bryant <gogobebe2@gmail.com> - 2013-09-16 16:33 -0700
  Re: How do I calculate a mean with python? Jugurtha Hadjar <jugurtha.hadjar@gmail.com> - 2013-09-17 00:52 +0100
  Re: How do I calculate a mean with python? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-09-16 23:55 +0000
  Re: How do I calculate a mean with python? MRAB <python@mrabarnett.plus.com> - 2013-09-17 01:01 +0100
  Re: How do I calculate a mean with python? Jugurtha Hadjar <jugurtha.hadjar@gmail.com> - 2013-09-17 01:08 +0100
  Re: How do I calculate a mean with python? Cameron Simpson <cs@zip.com.au> - 2013-09-17 09:59 +1000
  Re: How do I calculate a mean with python? Dave Angel <davea@davea.name> - 2013-09-17 00:50 +0000
  Re: How do I calculate a mean with python? Travis Griggs <travisgriggs@gmail.com> - 2013-09-17 08:25 -0700
  Re: How do I calculate a mean with python? William Bryant <gogobebe2@gmail.com> - 2013-09-17 12:44 -0700
  Re: How do I calculate a mean with python? William Bryant <gogobebe2@gmail.com> - 2013-09-17 12:45 -0700
  Re: How do I calculate a mean with python? William Bryant <gogobebe2@gmail.com> - 2013-09-17 13:10 -0700
    Re: How do I calculate a mean with python? Joel Goldstick <joel.goldstick@gmail.com> - 2013-09-17 17:02 -0400
    Re: How do I calculate a mean with python? MRAB <python@mrabarnett.plus.com> - 2013-09-17 22:26 +0100
      Re: How do I calculate a mean with python? William Bryant <gogobebe2@gmail.com> - 2013-09-17 14:31 -0700
        Re: How do I calculate a mean with python? Joel Goldstick <joel.goldstick@gmail.com> - 2013-09-17 19:49 -0400
  Re: How do I calculate a mean with python? Bryan Britten <britten.bryan@gmail.com> - 2013-09-17 18:53 -0700

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