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Re: Lucky numbers in Python

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From Ian Kelly <ian.g.kelly@gmail.com>
Date Wed, 29 Apr 2015 20:55:29 -0600
Subject Re: Lucky numbers in Python
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On Wed, Apr 29, 2015 at 6:01 PM, Cecil Westerhof <Cecil@decebal.nl> wrote:
> Op Thursday 30 Apr 2015 00:38 CEST schreef Ian Kelly:
>> In that case you can definitely omit the middle term of the slice,
>> which will be both more concise and clearer in intent, though
>> probably not significantly faster.
>
> It is certainly nit faster. It is even significantly slower. With the
> middle term lucky_numbers(int(1e6)) takes 0.13 seconds. Without it
> takes 14.3 seconds. Hundred times as long.

That would be rather surprising, since it's the same operation being
performed, so I did my own timing and came up with 0.25 seconds (best
of 3) with the middle term and 0.22 seconds without.

I suspect that you tested it as "del sieve[skip_count - 1 :
skip_count]" (which would delete only one item) rather than "del
sieve[skip_count - 1 :: skip_count]".

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Thread

Lucky numbers in Python Cecil Westerhof <Cecil@decebal.nl> - 2015-04-29 20:24 +0200
  Re: Lucky numbers in Python Ian Kelly <ian.g.kelly@gmail.com> - 2015-04-29 13:57 -0600
    Re: Lucky numbers in Python Cecil Westerhof <Cecil@decebal.nl> - 2015-04-29 23:45 +0200
      Re: Lucky numbers in Python Ian Kelly <ian.g.kelly@gmail.com> - 2015-04-29 16:38 -0600
        Re: Lucky numbers in Python Cecil Westerhof <Cecil@decebal.nl> - 2015-04-30 02:01 +0200
          Re: Lucky numbers in Python Ian Kelly <ian.g.kelly@gmail.com> - 2015-04-29 20:55 -0600
            Re: Lucky numbers in Python Cecil Westerhof <Cecil@decebal.nl> - 2015-04-30 08:34 +0200
      Re: Lucky numbers in Python Chris Kaynor <ckaynor@zindagigames.com> - 2015-04-29 15:56 -0700
    Re: Lucky numbers in Python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-30 10:11 +1000
      Re: Lucky numbers in Python Ian Kelly <ian.g.kelly@gmail.com> - 2015-04-29 21:08 -0600
  Re: Lucky numbers in Python Cecil Westerhof <Cecil@decebal.nl> - 2015-04-30 20:55 +0200
    Re: Lucky numbers in Python Dave Angel <davea@davea.name> - 2015-04-30 15:28 -0400

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