random.SystemRandom().randint() inefficient

[Cecil Westerhof]

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