sum up numbers in a list

[Fredrik Lundh]

sharon kim wrote:

> i have a list, for example;
> 
>  >>> L=[]
>  >>> L.append('10')
>  >>> L.append('15')
>  >>> L.append('20')
>  >>> len(L)
> 3
>  >>> print L
> ['10', '15', '20']
> 
> is there a way to sum up all the numbers in a list?  the number of 
> objects in the list is vary, around 50 to 60. all objects are 1 to 3 
> digit positive numbers.

the for-in statement is your friend:

     S = 0
     for item in L:
         S += int(item)

it can also be used in-line (this is called a "generator expression"):

     S = sum(int(v) for v in L)

or even hidden inside a built-in helper function:

     S = sum(map(int, L))

</F>