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Re: Python presentations

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Date Fri, 14 Sep 2012 22:19:22 +1000
Subject Re: Python presentations
From Chris Angelico <rosuav@gmail.com>
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On Fri, Sep 14, 2012 at 9:47 PM, Alexander Blinne <news@blinne.net> wrote:
> On 14.09.2012 00:38, Chris Angelico wrote:
>> On Fri, Sep 14, 2012 at 8:33 AM, Alexander Blinne <news@blinne.net> wrote:
>>> def powerlist(x,n):
>>>     if n==1:
>>>         return [1]
>>>     p = powerlist(x,n-1)
>>>     return p + [p[-1]*x]
>>
>> Eh, much simpler.
>>
>> def powerlist(x,n):
>>   return [x*i for i in xrange(n-1)]
>
> I suppose you meant:
>
> def powerlist(x,n):
>   return [x**i for i in xrange(n-1)]
>
> But this is less efficient, because it needs more multiplications (see
> Horner's method)

Err, yes, I did mean ** there. The extra multiplications may be
slower, but which is worse? Lots of list additions, or lots of integer
powers? In the absence of clear and compelling evidence, I'd be
inclined to go with the list comp - and what's more, to skip this
function altogether and use the list comp directly where it's needed.

ChrisA

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Python presentations andrea crotti <andrea.crotti.0@gmail.com> - 2012-09-13 17:00 +0100
  Re: Python presentations John Gordon <gordon@panix.com> - 2012-09-13 16:06 +0000
  Re: Python presentations mblume <foobar@invalid.invalid> - 2012-09-13 16:26 +0000
    Re: Python presentations 88888 Dihedral <dihedral88888@googlemail.com> - 2012-09-13 12:01 -0700
      Re: Python presentations Alexander Blinne <news@blinne.net> - 2012-09-14 00:33 +0200
        Re: Python presentations Chris Angelico <rosuav@gmail.com> - 2012-09-14 08:38 +1000
          Re: Python presentations 88888 Dihedral <dihedral88888@googlemail.com> - 2012-09-13 22:57 -0700
          Re: Python presentations 88888 Dihedral <dihedral88888@googlemail.com> - 2012-09-13 22:57 -0700
          Re: Python presentations Alexander Blinne <news@blinne.net> - 2012-09-14 13:47 +0200
            Re: Python presentations Chris Angelico <rosuav@gmail.com> - 2012-09-14 22:19 +1000
              Re: Python presentations Alexander Blinne <news@blinne.net> - 2012-09-16 18:13 +0200
                Re: Python presentations Chris Angelico <rosuav@gmail.com> - 2012-09-17 02:19 +1000
                Re: Python presentations Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-09-16 17:35 +0000
                Re: Python presentations Alexander Blinne <news@blinne.net> - 2012-09-17 10:39 +0200
  Re: Python presentations Miki Tebeka <miki.tebeka@gmail.com> - 2012-09-13 15:58 -0700
    Re: Python presentations Andrea Crotti <andrea.crotti.0@gmail.com> - 2012-09-14 00:15 +0100
  Re: Python presentations Miki Tebeka <miki.tebeka@gmail.com> - 2012-09-13 15:58 -0700

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