[Tutor] Why does counting to 20 million stress my computer? (original) (raw)

Danny Yoo dyoo at hkn.eecs.berkeley.edu
Sat Jul 17 20:47:40 CEST 2004

using range(50000000): 18.281 seconds using xrange(50000000): 13.516 seconds

You sure you didnt type in 500000000 ;) So xrange is definitely quicker. Is it better to use xrange all the time in place of range then ?

Hi Nick,

It depends on what we need. grin

xrange() returns an iterable object that's wonderful if we want to go through the integers in order, one at a time. But say we wanted to do something, like grab a randomized list of numbers:

import random numbers = range(52) random.shuffle(numbers) numbers [1, 43, 18, 48, 47, 0, 46, 36, 13, 9, 20, 27, 42, 45, 10, 26, 19, 38, 16, 35, 25, 32, 17, 22, 23, 29, 6, 41, 14, 30, 15, 40, 50, 28, 3, 49, 12, 39, 5, 11, 33, 4, 34, 37, 24, 21, 2, 7, 8, 51, 31, 44] ###

In this case, range() is a good tool for this job, because it gives us a list that we can munge up with random.shuffle(). xrange() gives us just an iterable that's specialized only to do sequential counting, so it wouldn't be as appropriate here.

Personally, I usually do stick with range(), and completely disregard efficiency until I really need it.

Hope this helps!

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