random.SystemRandom().randint() inefficient
Cecil Westerhof
Cecil at decebal.nl
Wed Jul 27 15:16:23 EDT 2022
Roel Schroeven <roel at roelschroeven.net> writes:
> Cecil Westerhof via Python-list schreef op 27/07/2022 om 17:43:
>> "Michael F. Stemper" <michael.stemper at gmail.com> writes:
>>
>> > This is orthogonal to your question, but might be of some use to you:
>> >
>> > The combination of using len(to_try) as an argument to randint() and
>> > saving the output to a variable named "index" suggests that you might
>> > be setting up to select a random element from to_try, as in:
>> > something = to_try[index]
>> >
>> > If that is the case, you might want to consider using random.choice() instead:
>> >
>> > >>> from random import choice
>> > >>> to_try = [2,3,5,7,11,13,"seventeen",19]
>> > >>> choice(to_try)
>> > 2
>> > >>> choice(to_try)
>> > 'seventeen'
>> > >>> choice(to_try)
>> > 13
>> > >>> choice(to_try)
>> > 5
>> > >>>
>>
>> Yes, I try to select a random element, but it has also to be removed,
>> because an element should not be used more as once.
>> This is the code I use:
>> # index = randbelow(len(to_try))
>> index = randrange(len(to_try))
>> found = permutation[to_try.pop(index)]
> Do you know in advance how many items you'll need, or maybe an upper
> limit on the amount? In that case it might be more efficient to use
> random.sample(to_try, k=nr_items_needed).
Something else to try. :-)
And yes: I will be using half of the list.
--
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof
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