Comments on: Find the Mean/Average of a Number List in Python

By: Bhanu

Bhanu — Mon, 23 Jan 2012 21:17:18 +0000

This code worked.

Thanks a lot!

By: lvc

lvc — Wed, 13 Apr 2011 04:37:16 +0000

For python 2.2-2.7, you can just do:
from ___future___ import division
And then sum(nums)/len(nums) will work as expected – no need to convert anything to a float. This is the default in 3.0 on.

By: admin

admin — Sat, 09 Apr 2011 23:04:25 +0000

Yeah, that’s a valid point. It should be “not a number.” I’ve updated the code based on your suggestion.

By: Mean of no values

Mean of no values — Fri, 08 Apr 2011 09:35:29 +0000

Is there a definition for mean of no values?
It is not obvious to me that the mean of an empty sequence is 0.0, perhaps division by zero (or a specific exception) is reasonable. It might depend on the use of the function.

Since division by 0 triggers an exception in Python, it might be a good idea to not check in many cases, and use that as a precondition. In other languages were division by 0 will yield NAN and INF which can then be used silently, the check is more important.

By: check your own code

check your own code — Tue, 30 Nov 2010 10:28:26 +0000

dae, you should check your own code.

It should be:

return float( sum(nums) ) / len(nums)

What you had will first calculate sum/len as an integer and then convert it to a float. You end up with interger_result.0

By: pk

pk — Sat, 15 May 2010 02:35:05 +0000

oh wow. that’s a shocker

By: not division by zero yet

not division by zero yet — Thu, 13 May 2010 15:32:25 +0000

Your function has input argument numberList but refers to it as floatNums (a variable that is defined in another post therefore outside the scope of your function). There will never be a division by zero because the interpreter will not be able to proceed to the division.

By: pk

pk — Fri, 05 Feb 2010 16:10:53 +0000

hah, division by zero. how embarrasing.

By: dae

dae — Fri, 05 Feb 2010 02:23:04 +0000

pk is right, python has a built in sum() function, although his code example is sloppy.
def mean(nums):
if len(nums):
return float( sum(nums) / len(nums))
else:
return 0.0

By: pk

pk — Fri, 01 May 2009 13:34:22 +0000

couldnt you just do

def mean(numberList):
return float(sum(floatNums)) / len(numberList)