slice notation as values?
bonono at gmail.com
bonono at gmail.com
Mon Dec 12 11:20:54 CET 2005
Antoon Pardon wrote:
> Suppose I have a list with 10 000 elements and I want
> the sum of the first 100, the sum of the second 100 ...
>
> One way to do that would be:
>
> for i in xrange(0,10000,100):
> sum(itertools.islice(lst, i, i+100))
>
> But itertools.islice would each time start from the begining
> of the list and iterate over i elements before giving 100
> elements to sum. Which would make this implementation O(n^2)
> instead of O(n).
Can you use iter for this situation ?
a=iter(lst)
for i in xrange(0,10000,100):
sum(itertools.islice(a,100))
More information about the Python-list
mailing list