osdir.com


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

itertools cycle() docs question


On 8/21/19 2:32 PM, Calvin Spealman wrote:
> The point is to demonstrate the effect, not the specific implementation.

Once you've gone through the iterable once, it's falsey,
which means that the while loop will end.  But if you copy
all the elements to a real list, then the while loop is
infinite.

Dan

> On Wed, Aug 21, 2019 at 2:30 PM Tobiah <toby at tobiah.org> wrote:
> 
>> In the docs for itertools.cycle() there is
>> a bit of equivalent code given:
>>
>>      def cycle(iterable):
>>          # cycle('ABCD') --> A B C D A B C D A B C D ...
>>          saved = []
>>          for element in iterable:
>>              yield element
>>              saved.append(element)
>>          while saved:
>>              for element in saved:
>>                  yield element
>>
>>
>> Is that really how it works?  Why make
>> the copy of the elements?  This seems
>> to be equivalent:
>>
>>
>>      def cycle(iterable):
>>          while iterable:
>>              for thing in iterable:
>>                  yield thing
>> --
>> https://mail.python.org/mailman/listinfo/python-list
>>
> 
>