# [Tutor] Summing a list of numbers / writing small functions

Danny Yoo dyoo@hkn.eecs.berkeley.edu
Fri Apr 11 14:07:01 2003

```> > How can I simplify this lines:
> >     > sum = 0
> >     > myList = [1,2,3,4,5,6]
> >     > for each in myList:
> >     >    sum += each
> >
> > Into shorter, more elegant line(s)?
>
> Although Albert has shown you how to do this with reduce() I don't
> actually think there is any need to shorten or make this more elegant.
>
> compare
> sum = reduce(operator.add, myList)
> with
> for x in myList: sum += x
>
> which is shorter? which is more elegant?

Hello!

I think both ways work perfectly well.  The important thing, though, is to
see if we do this summation frequently.  If so, it's probably worth it to
define a add_all() function to capture that idea of adding up elements in
a list.

We've seen two ways of doing it:

###
sum = 0
for x in myList:
sum += x
return sum
###

and

###
###

As soon as we have some sort of definition for summation --- as soon as we
give it a name --- we can use it as part of our language!

###