Bugs item #1621367, was opened at 2006-12-23 17:04 Message generated for change (Comment added) made by dallison You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1621367&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Extension Modules Group: Python 2.5 Status: Open Resolution: None Priority: 5 Private: No Submitted By: Msword (msword) Assigned to: Nobody/Anonymous (nobody) Summary: random import works? Initial Comment: I'm just starting working with python, and it seems that random.choice() isn't all that random. After running the program(attached) a few times, each and every time it selects 1 < 2 < 3 < 4 < 5 and I can expect this to happen, meaning it isn't all that random. Email: [EMAIL PROTECTED] Thanks ---------------------------------------------------------------------- Comment By: Dennis Allison (dallison) Date: 2006-12-23 18:32 Message: Logged In: YES user_id=31903 Originator: NO I believe the problem is with your test framework and not with random.choice(). The library function random.choice( seq ) selects, using a uniform distribution, one item from the sequence at each call. By the law of large numbers, if you have K items in the sequence, each should be returned K/N times, on average, after N calls. You should expect deviations even for fairly large N. If you want to test the randomess, use a chi-square test to test against the hypothes of uniform random selection with replacement. Of course there are many other statistical properties which ought to be checked, for example, the distribution of runs. Consider the program: import random dist = [0,0,0,0,0] for i in range(100000): j = random.choice([0,1,2,3,4]) dist[j] += 1 print dist which prints the distribution observed for each choice. With 100000 tries you'd expect each one to appear (on average) 20000 time. Running it on my a three times gives: [19839, 19871, 19996, 20035, 20259] [20043, 19870, 20025, 20109, 19953] [19947, 20033, 19970, 20111, 19939] ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1621367&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com