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Re: Python Random vs. Cython C Rand for Dice Rolls

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  Re: Python Random vs. Cython C Rand for Dice Rolls Chris Angelico <rosuav@gmail.com> - 2015-06-08 03:23 +1000
    Re: Python Random vs. Cython C Rand for Dice Rolls Cecil Westerhof <Cecil@decebal.nl> - 2015-06-07 21:34 +0200

#92277 — Re: Python Random vs. Cython C Rand for Dice Rolls

On Mon, Jun 8, 2015 at 3:17 AM, C.D. Reimer <chris@cdreimer.com> wrote:
> This is the Python script that takes ~197 seconds to complete.
>
> import random, time
>
> startTime = time.time()
>
> f = [0] * 12
>
> for i in range(50000000):
>
>     a = random.randint(1,6)
>
>     b = random.randint(1,6)
>
>     f[(a + b) - 1] += 1
>
> print "\nTOTAL SPOTS","\tNUMBER OF TIMES\n"
>
> for i in range(1,12):
>
>     print ' ' + str(i + 1), '\t\t ', f[i]
>
> print '\n', time.time() - startTime

Before you go any further, can you just try this script, please, and
see how long it takes to run?

import random, time
startTime = time.time()
for i in range(50000000):
    pass
print '\n', time.time() - startTime

I know, seems a stupid thing to try, right? But you're using Python 2,
as evidenced by the print statements, and that means that range() is
constructing a 50M element list. It's entirely possible that that's a
significant part of your time - allocating all that memory, populating
it, and then disposing of it at the end (maybe).

Maybe it'll turn out not to be significant, but there's only one way
to find out.

ChrisA

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#92298

On Sunday  7 Jun 2015 19:23 CEST, Chris Angelico wrote:

> On Mon, Jun 8, 2015 at 3:17 AM, C.D. Reimer <chris@cdreimer.com> wrote:
>> This is the Python script that takes ~197 seconds to complete.
>>
>> import random, time
>>
>> startTime = time.time()
>>
>> f = [0] * 12
>>
>> for i in range(50000000):
>>
>> a = random.randint(1,6)
>>
>> b = random.randint(1,6)
>>
>> f[(a + b) - 1] += 1
>>
>> print "\nTOTAL SPOTS","\tNUMBER OF TIMES\n"
>>
>> for i in range(1,12):
>>
>> print ' ' + str(i + 1), '\t\t ', f[i]
>>
>> print '\n', time.time() - startTime
>
> Before you go any further, can you just try this script, please, and
> see how long it takes to run?
>
> import random, time
> startTime = time.time()
> for i in range(50000000):
> pass
> print '\n', time.time() - startTime
>
> I know, seems a stupid thing to try, right? But you're using Python
> 2, as evidenced by the print statements, and that means that range()
> is constructing a 50M element list. It's entirely possible that
> that's a significant part of your time - allocating all that memory,
> populating it, and then disposing of it at the end (maybe).
>
> Maybe it'll turn out not to be significant, but there's only one way
> to find out.

I tried this in 2 and 3. In 3 it takes 3.13 seconds and 2 7.5 seconds.
A significant difference, but not in the whole of what he was trying
to do I think.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof

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