Re: [Tutor] printing the random seed?
Danny Yoo wrote: On Thu, 2 Feb 2006, kevin parks wrote: Danny (hope you are good!) co, I see that biz about random.seed()... but in the absence of setting that ... does it just grab a value from the system clock? Yes. Here's what the documentation says officially: current system time is also used to initialize the generator when the module is first imported As of Python 2.4, random.seed() will attempt to use os.urandom() to initialize the seed; if that is not available it uses the system time. Is there a way to just let it generate it's usual, known seed... but then observe what that is in case you get an especially good run of data? We can call seed() explicitely using system time then when we start using the random module, and if the results are interesting, we report that initial seed value too. That way, by knowing the initial conditions, we can reproduce the results. Here is the code from random.py that initializes the seed (a): try: a = long(_hexlify(_urandom(16)), 16) except NotImplementedError: import time a = long(time.time() * 256) # use fractional seconds Kent ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] printing the random seed?
I am having some fun with python and making multiple runs on an algorhythm and sometimes getting some fun stuff that i would like to be able to reproduce, but there are some random elements in it. I wonder is there a way to see the random seed, and make note of it so that you could then set the seed for a subsequent run to get the same (initially) random results? Hi Kevin, Sure; take a look at the seed() function in the random module. http://www.python.org/doc/lib/module-random.html#l2h-1298 Just set it to some consistant value at the very beginning of your program, and you should then see duplicate results between program runs. You could also probably do something with random.getstate() and random.setstate(), but it's probably a bit simpler just to inject a known seed value into the pseudorandom generator. (Hi Danny, if you are still here!) *wave wave* Good luck! ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] printing the random seed?
Danny (hope you are good!) co, I see that biz about random.seed()... but in the absence of setting that ... does it just grab a value from the system clock? Is there a way to just let it generate it's usual, known seed... but then observe what that is in case you get an especially good run of data? like i clearly can't just go: zeed = random.seed() print zeed = , zeed hmm... cheers, -[kp]-- ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] printing the random seed?
On Thu, 2 Feb 2006, kevin parks wrote: Danny (hope you are good!) co, I see that biz about random.seed()... but in the absence of setting that ... does it just grab a value from the system clock? Yes. Here's what the documentation says officially: current system time is also used to initialize the generator when the module is first imported Is there a way to just let it generate it's usual, known seed... but then observe what that is in case you get an especially good run of data? We can call seed() explicitely using system time then when we start using the random module, and if the results are interesting, we report that initial seed value too. That way, by knowing the initial conditions, we can reproduce the results. ## import time import random t = time.time() random.seed(t) random.random() 0.39026231885512619 random.random() 0.72296902513427053 random.random() 0.48408173490166762 t 1138866167.719857 random.seed(t) random.random() 0.39026231885512619 random.random() 0.72296902513427053 random.random() 0.48408173490166762 ## ___ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
