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Re: Newbie looking for elegant solution

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> On Mar 24, 2015, at 8:28 PM, Chris Angelico <rosuav@gmail.com> wrote:
> 
> On Wed, Mar 25, 2015 at 2:13 PM,  <otaksoftspamtrap@gmail.com> wrote:
>> I have a list containing 9600 integer elements - each integer is either 0 or 1.
>> 
>> Starting at the front of the list, I need to combine 8 list elements into 1 by treating them as if they were bits of one byte with 1 and 0 denoting bit on/off (the 8th element would be the rightmost bit of the first byte).
>> 
>> Speed is not of utmost importance - an elegant solution is. Any suggestions?
> 
> Oooh fun!
> 
>>>> l = [1, 0, 1, 1, 0, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1]
>>>> list(int(''.join(str(i) for i in l),2).to_bytes(len(l)//8,'big'))
> [177, 105, 117]
> 
> Convert it into a string, convert the string to an integer
> (interpreting it as binary), then convert the integer into a series of
> bytes, and interpret those bytes as a list of integers.
> 
> Example works in Python 3. For Python 2, you'll need ord() to get the
> integers at the end.
> 
> I'm not sure how elegant this is, but it's a fun trick to play with :)
> 
> Next idea please! I love these kinds of threads.

Me too. These are my favorite threads. Here’s my entry:

[sum(b << (7 - i) for i, b in enumerate(bits)) for bits in zip(*[l[n::8] for n in range(8)])]

I think there has to be a better way to do the left hand part, but I liked the zipped iterators on 8 slices.

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Newbie looking for elegant solution otaksoftspamtrap@gmail.com - 2015-03-24 20:13 -0700
  Re: Newbie looking for elegant solution Chris Angelico <rosuav@gmail.com> - 2015-03-25 14:28 +1100
    Re: Newbie looking for elegant solution otaksoftspamtrap@gmail.com - 2015-03-24 20:31 -0700
  Re: Newbie looking for elegant solution Paul Rubin <no.email@nospam.invalid> - 2015-03-24 21:04 -0700
    Re: Newbie looking for elegant solution kai.peters@gmail.com - 2015-03-24 21:19 -0700
    Re: Newbie looking for elegant solution Chris Angelico <rosuav@gmail.com> - 2015-03-25 15:19 +1100
      Re: Newbie looking for elegant solution kai.peters@gmail.com - 2015-03-24 21:46 -0700
        Re: Newbie looking for elegant solution Chris Angelico <rosuav@gmail.com> - 2015-03-25 16:05 +1100
        Re: Newbie looking for elegant solution Ben Finney <ben+python@benfinney.id.au> - 2015-03-25 16:28 +1100
        Re: Newbie looking for elegant solution Paul Rubin <no.email@nospam.invalid> - 2015-03-24 22:52 -0700
          Re: Newbie looking for elegant solution Rustom Mody <rustompmody@gmail.com> - 2015-03-24 23:32 -0700
  Re: Newbie looking for elegant solution Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-25 16:24 +1100
  Re: Newbie looking for elegant solution Dave Farrance <DaveFarrance@OMiTTHiSyahooANDTHiS.co.uk> - 2015-03-25 06:05 +0000
  Re: Newbie looking for elegant solution Travis Griggs <travisgriggs@gmail.com> - 2015-03-25 11:49 -0700
  Re: Newbie looking for elegant solution kai.peters@gmail.com - 2015-03-25 16:14 -0700
    Re: Newbie looking for elegant solution Paul Rubin <no.email@nospam.invalid> - 2015-03-25 16:30 -0700
    Re: Newbie looking for elegant solution Irmen de Jong <irmen.NOSPAM@xs4all.nl> - 2015-03-26 00:34 +0100
  Re: Newbie looking for elegant solution kai.peters@gmail.com - 2015-03-25 17:38 -0700
    Re: Newbie looking for elegant solution Paul Rubin <no.email@nospam.invalid> - 2015-03-25 18:09 -0700
      Re: Newbie looking for elegant solution kai.peters@gmail.com - 2015-03-25 18:29 -0700
        Re: Newbie looking for elegant solution Paul Rubin <no.email@nospam.invalid> - 2015-03-25 19:53 -0700

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