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Re: l = range(int(1E9))

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From Mark Lawrence <breamoreboy@yahoo.co.uk>
Subject Re: l = range(int(1E9))
Date Sat, 02 May 2015 20:15:24 +0100
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On 02/05/2015 19:34, BartC wrote:
> On 02/05/2015 17:39, Mark Lawrence wrote:
>> On 02/05/2015 17:17, BartC wrote:
>>> On 02/05/2015 16:40, Mark Lawrence wrote:
>
>
>>>> for item in items:
>>>>
>>>> When did this change, or has it always been this way and you were
>>>> simply
>>>> using an idiom from other languages?
>>>
>>> Your example is the equivalent of 'forall' in other languages, where you
>>> iterate over the values of some collection of data.
>>>
>>> I agree that most for-loops in Pythonic code probably fall into that
>>> category.
>>>
>>> But for looping over a simple integer range, then using 'range' to
>>> denote the range (and build a list as it used to do), was how it was
>>> done. And earlier on people would have been porting coding code to
>>> Python at which point a straightforward 'for i=a to b' loop suddenly
>>> acquired a substantial overhead it didn't have before!
>>>
>>
>> All you are saying is that they didn't bother reading the docs and
>> learning how to write a *PYTHON* for loop.  Failing that don't bother
>> using range, just directly convert your (say) C loop into Python.  I
>> really don't see any issue here at all.
>
> OK, so it's the programmer's fault if as fundamental a concept as a
> for-loop ranging over integers is implemented inefficiently. He has to
> transform it into high-level terms, or has to reconstruct it somehow
> using a while-loop and an incrementing loop index.
>
> Now I understand (why Python has been beset for so long with performance
> problems, if that is a typical attitude!).
>
> BTW, why did they introduce the 'xrange' thing; for fun? Or did someone
> realise there might have been an issue after all?
>
> (I tried an empty loop counting to 1 billion in Python 2.x, using 'for i
> in range'. It ran out of memory. Counting to 100 million instead, it
> worked, but still used a massive 1.5GB RAM while doing so (and took 6
> seconds to count to 100M, not too bad for Python)
>
> Outside Python, it might typically take a few seconds to count to 1
> billion, and would use virtually no memory.
>
> Why would anyone want to loop over all those numbers instead of
> iterating over actual data? For any number of reasons. Counting how many
> happy numbers are in that range for one!)
>

I give up.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence

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Thread

l = range(int(1E9)) Cecil Westerhof <Cecil@decebal.nl> - 2015-04-30 18:06 +0200
  Re: l = range(int(1E9)) Grant Edwards <invalid@invalid.invalid> - 2015-04-30 16:33 +0000
    Re: l = range(int(1E9)) Cecil Westerhof <Cecil@decebal.nl> - 2015-04-30 19:26 +0200
      Re: l = range(int(1E9)) Ben Finney <ben+python@benfinney.id.au> - 2015-05-01 03:41 +1000
        Re: l = range(int(1E9)) Cecil Westerhof <Cecil@decebal.nl> - 2015-04-30 20:44 +0200
    Re: l = range(int(1E9)) Roel Schroeven <roel@roelschroeven.net> - 2015-04-30 21:40 +0200
  Re: l = range(int(1E9)) Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-04-30 16:55 +0000
    Re: l = range(int(1E9)) Ben Finney <ben+python@benfinney.id.au> - 2015-05-01 03:20 +1000
      Re: l = range(int(1E9)) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-01 15:20 +1000
        Re: l = range(int(1E9)) Cecil Westerhof <Cecil@decebal.nl> - 2015-05-01 08:08 +0200
      Re: l = range(int(1E9)) BartC <bc@freeuk.com> - 2015-05-02 16:26 +0100
        Re: l = range(int(1E9)) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-02 16:40 +0100
          Re: l = range(int(1E9)) BartC <bc@freeuk.com> - 2015-05-02 17:17 +0100
            Re: l = range(int(1E9)) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-02 17:39 +0100
              Re: l = range(int(1E9)) BartC <bc@freeuk.com> - 2015-05-02 19:34 +0100
                Re: l = range(int(1E9)) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-02 20:15 +0100
                Re: l = range(int(1E9)) Marko Rauhamaa <marko@pacujo.net> - 2015-05-02 22:26 +0300
                Re: l = range(int(1E9)) BartC <bc@freeuk.com> - 2015-05-02 20:51 +0100
                Re: l = range(int(1E9)) Joel Goldstick <joel.goldstick@gmail.com> - 2015-05-02 17:21 -0400
                Re: l = range(int(1E9)) Ian Kelly <ian.g.kelly@gmail.com> - 2015-05-02 15:31 -0600
                Re: l = range(int(1E9)) Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-05-02 21:40 +0000
                Re: l = range(int(1E9)) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-02 23:26 +0100
                Re: l = range(int(1E9)) BartC <bc@freeuk.com> - 2015-05-02 23:33 +0100
                Re: l = range(int(1E9)) Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-05-03 00:13 +0000
                Re: l = range(int(1E9)) Michael Torrie <torriem@gmail.com> - 2015-05-02 20:07 -0600
                Re: l = range(int(1E9)) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-03 03:16 +0100
                Re: l = range(int(1E9)) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-03 21:16 +1000
                Re: l = range(int(1E9)) Chris Angelico <rosuav@gmail.com> - 2015-05-03 21:30 +1000
                Re: l = range(int(1E9)) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-03 19:36 +0100
                Re: l = range(int(1E9)) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-03 21:15 +1000
                Re: l = range(int(1E9)) Chris Angelico <rosuav@gmail.com> - 2015-05-03 21:29 +1000
                Re: l = range(int(1E9)) Terry Reedy <tjreedy@udel.edu> - 2015-05-02 19:26 -0400
                Re: l = range(int(1E9)) Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-05-03 00:01 +0000
                Re: l = range(int(1E9)) Terry Reedy <tjreedy@udel.edu> - 2015-05-02 23:18 -0400
                Re: l = range(int(1E9)) Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2015-05-03 03:40 +0000
                Re: l = range(int(1E9)) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-03 21:05 +1000
                Re: l = range(int(1E9)) Terry Reedy <tjreedy@udel.edu> - 2015-05-02 19:51 -0400
                Re: l = range(int(1E9)) Ian Kelly <ian.g.kelly@gmail.com> - 2015-05-02 22:51 -0600
                Re: l = range(int(1E9)) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-03 21:21 +1000
                Re: l = range(int(1E9)) Marko Rauhamaa <marko@pacujo.net> - 2015-05-02 22:15 +0300
            Re: l = range(int(1E9)) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-03 20:32 +1000
              Re: l = range(int(1E9)) Chris Angelico <rosuav@gmail.com> - 2015-05-03 20:59 +1000
        Re: l = range(int(1E9)) Terry Reedy <tjreedy@udel.edu> - 2015-05-02 18:41 -0400
    Re: l = range(int(1E9)) Cecil Westerhof <Cecil@decebal.nl> - 2015-04-30 19:28 +0200
  Re: l = range(int(1E9)) Terry Reedy <tjreedy@udel.edu> - 2015-04-30 13:02 -0400
  Re: l = range(int(1E9)) Gary Herron <gherron@digipen.edu> - 2015-04-30 10:05 -0700
    Re: l = range(int(1E9)) Rob Gaddi <rgaddi@technologyhighland.invalid> - 2015-04-30 17:12 +0000
      Re: l = range(int(1E9)) Cecil Westerhof <Cecil@decebal.nl> - 2015-04-30 20:50 +0200
        Re: l = range(int(1E9)) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-04-30 21:53 +0100
          Re: l = range(int(1E9)) ElChino <elchino@cnn.cn> - 2015-04-30 23:23 +0200
            Re: l = range(int(1E9)) Chris Angelico <rosuav@gmail.com> - 2015-05-01 08:45 +1000
              Re: l = range(int(1E9)) ElChino <elchino@cnn.cn> - 2015-05-01 01:03 +0200
            Re: l = range(int(1E9)) Ben Finney <ben+python@benfinney.id.au> - 2015-05-01 09:12 +1000
              Re: l = range(int(1E9)) Cecil Westerhof <Cecil@decebal.nl> - 2015-05-01 07:04 +0200
                Re: l = range(int(1E9)) Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2015-05-01 13:15 +0200
                Re: l = range(int(1E9)) Cecil Westerhof <Cecil@decebal.nl> - 2015-05-01 14:22 +0200
                Re: l = range(int(1E9)) Terry Reedy <tjreedy@udel.edu> - 2015-05-01 22:00 -0400
            Use ‘python2’ or ‘python3’, explicit is better than implicit  (was: l = range(int(1E9))) Ben Finney <ben+python@benfinney.id.au> - 2015-05-01 09:19 +1000
              Re: Use 'python2' or 'python3', explicit is better than implicit  (was: l = range(int(1E9))) Rustom Mody <rustompmody@gmail.com> - 2015-04-30 19:24 -0700
            Re: l = range(int(1E9)) Chris Angelico <rosuav@gmail.com> - 2015-05-01 09:23 +1000
          Re: l = range(int(1E9)) Cecil Westerhof <Cecil@decebal.nl> - 2015-05-01 06:19 +0200
            Re: l = range(int(1E9)) Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-05-01 05:41 +0100
            Re: l = range(int(1E9)) Michael Torrie <torriem@gmail.com> - 2015-05-01 07:25 -0600
              Re: l = range(int(1E9)) Cecil Westerhof <Cecil@decebal.nl> - 2015-05-01 16:12 +0200
  Re: l = range(int(1E9)) Gisle Vanem <gvanem@yahoo.no> - 2015-04-30 20:23 +0200
    Re: l = range(int(1E9)) alister <alister.nospam.ware@ntlworld.com> - 2015-04-30 18:48 +0000
      Re: l = range(int(1E9)) Dave Angel <davea@davea.name> - 2015-04-30 14:59 -0400
        Re: l = range(int(1E9)) Cecil Westerhof <Cecil@decebal.nl> - 2015-04-30 22:18 +0200
          Re: l = range(int(1E9)) Tim Chase <python.list@tim.thechases.com> - 2015-04-30 16:41 -0500
            Re: l = range(int(1E9)) Cecil Westerhof <Cecil@decebal.nl> - 2015-05-01 07:19 +0200
  Re: l = range(int(1E9)) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-01 14:42 +1000
    Re: l = range(int(1E9)) Cecil Westerhof <Cecil@decebal.nl> - 2015-05-01 07:13 +0200
    Re: l = range(int(1E9)) Tony the Tiger <tony@tiger.invalid> - 2015-05-02 21:28 +0000
      Re: l = range(int(1E9)) Ian Kelly <ian.g.kelly@gmail.com> - 2015-05-02 15:32 -0600
      Re: l = range(int(1E9)) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-05-03 20:56 +1000

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