Re: what does 'a=b=c=[]' do

From	Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de>
Newsgroups	comp.lang.python
Subject	Re: what does 'a=b=c=[]' do
Date	2011-12-24 19:49 +0100
Organization	A newly installed InterNetNews server
Message-ID	<jd53c8$om1$1@r03.glglgl.gl> (permalink)
References	<18f78d0d-1e70-4c7b-9033-1422e6edb6db@t13g2000yqg.googlegroups.com>

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Am 21.12.2011 23:25 schrieb Eric:

> Is it true that if I want to create an array or arbitrary size such
> as:
>     for a in range(n):
>        x.append(<some function...>)
>
> I must do this instead?
>     x=[]
>     for a in range(n):
>        x.append(<some function...>)

Of course - your x must exist before using it.

 > Now to my actual question.  I need to do the above for multiple arrays
> (all the same, arbitrary size).  So I do this:
>     x=y=z=[]
>     for a in range(n):
>        x.append(<some function...>)
>        y.append(<some other function...>)
>        z.append(<yet another function...>)
> Also, is there a more pythonic way to do "x=[], y=[], z=[]"?

You could do:

def create_xyz(n):
     for a in range(n):
         yield <some function...>, <some other function...>, \
		<yet another function...>)

x, y, z = zip(*create_xyz(11))

or, if you want x, y, z to be lists,

x, y, z = [list(i) for i in zip(*create_xyz(11))]

.


Thomas

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what does 'a=b=c=[]' do Eric <einazaki668@yahoo.com> - 2011-12-21 14:25 -0800
  Re: what does 'a=b=c=[]' do Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2011-12-21 18:20 -0500
    Re: what does 'a=b=c=[]' do Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-21 23:48 +0000
      Re: what does 'a=b=c=[]' do Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2011-12-24 19:41 +0100
        Re: what does 'a=b=c=[]' do Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-25 13:16 +0000
    Re: what does 'a=b=c=[]' do Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2011-12-24 19:45 +0100
  Re: what does 'a=b=c=[]' do Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-21 23:44 +0000
    Re: what does 'a=b=c=[]' do Eric <einazaki668@yahoo.com> - 2011-12-22 20:27 -0800
  Re: what does 'a=b=c=[]' do alex23 <wuwei23@gmail.com> - 2011-12-21 16:50 -0800
    Re: what does 'a=b=c=[]' do Rolf Camps <rolf@roce.be> - 2011-12-22 09:51 +0100
      Re: what does 'a=b=c=[]' do alex23 <wuwei23@gmail.com> - 2011-12-22 18:10 -0800
        Re: what does 'a=b=c=[]' do Ian Kelly <ian.g.kelly@gmail.com> - 2011-12-22 19:59 -0700
          Re: what does 'a=b=c=[]' do alex23 <wuwei23@gmail.com> - 2011-12-22 19:40 -0800
            Re: what does 'a=b=c=[]' do Chris Angelico <rosuav@gmail.com> - 2011-12-23 15:25 +1100
            Re: what does 'a=b=c=[]' do Ian Kelly <ian.g.kelly@gmail.com> - 2011-12-22 22:22 -0700
              Re: what does 'a=b=c=[]' do alex23 <wuwei23@gmail.com> - 2011-12-22 22:00 -0800
        Re: what does 'a=b=c=[]' do rusi <rustompmody@gmail.com> - 2011-12-23 00:38 -0800
          Re: what does 'a=b=c=[]' do Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-23 09:39 +0000
            Re: what does 'a=b=c=[]' do rusi <rustompmody@gmail.com> - 2011-12-23 02:22 -0800
              Re: what does 'a=b=c=[]' do Robert Kern <robert.kern@gmail.com> - 2011-12-23 13:10 +0000
                Re: what does 'a=b=c=[]' do rusi <rustompmody@gmail.com> - 2011-12-23 05:23 -0800
                Re: what does 'a=b=c=[]' do Robert Kern <robert.kern@gmail.com> - 2011-12-23 13:53 +0000
                Re: what does 'a=b=c=[]' do rusi <rustompmody@gmail.com> - 2011-12-23 06:57 -0800
                Re: what does 'a=b=c=[]' do Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-23 15:33 +0000
                Re: what does 'a=b=c=[]' do rusi <rustompmody@gmail.com> - 2011-12-23 07:59 -0800
          Re: what does 'a=b=c=[]' do Ethan Furman <ethan@stoneleaf.us> - 2011-12-23 00:49 -0800
          Re: what does 'a=b=c=[]' do Chris Angelico <rosuav@gmail.com> - 2011-12-23 20:59 +1100
            Re: what does 'a=b=c=[]' do rusi <rustompmody@gmail.com> - 2011-12-23 02:31 -0800
              Timeout when calling COM objects on Windows Wong Wah Meng-R32813 <r32813@freescale.com> - 2011-12-23 11:20 +0000
              Re: what does 'a=b=c=[]' do Michael Torrie <torriem@gmail.com> - 2011-12-23 10:23 -0700
            Re: what does 'a=b=c=[]' do Neil Cerutti <neilc@norwich.edu> - 2011-12-23 13:10 +0000
              Re: what does 'a=b=c=[]' do Neil Cerutti <neilc@norwich.edu> - 2011-12-23 13:13 +0000
                Early and late binding [was Re: what does 'a=b=c=[]' do] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-23 15:49 +0000
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] Chris Angelico <rosuav@gmail.com> - 2011-12-24 02:55 +1100
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-23 22:32 +0000
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] Chris Angelico <rosuav@gmail.com> - 2011-12-24 09:50 +1100
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-24 08:11 +0000
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] Roy Smith <roy@panix.com> - 2011-12-23 11:15 -0500
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] alex23 <wuwei23@gmail.com> - 2011-12-24 05:43 -0800
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] Mel Wilson <mwilson@the-wire.com> - 2011-12-23 11:27 -0500
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] alex23 <wuwei23@gmail.com> - 2011-12-24 05:52 -0800
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] Neil Cerutti <neilc@norwich.edu> - 2011-12-23 17:03 +0000
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-24 08:25 +0000
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] alex23 <wuwei23@gmail.com> - 2011-12-24 06:08 -0800
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] Devin Jeanpierre <jeanpierreda@gmail.com> - 2011-12-24 18:25 -0500
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] alex23 <wuwei23@gmail.com> - 2011-12-24 16:10 -0800
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] Devin Jeanpierre <jeanpierreda@gmail.com> - 2011-12-24 19:32 -0500
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] rusi <rustompmody@gmail.com> - 2011-12-24 19:22 -0800
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] Lie Ryan <lie.1296@gmail.com> - 2011-12-25 15:12 +1100
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] Devin Jeanpierre <jeanpierreda@gmail.com> - 2011-12-23 19:24 -0500
                Re: Early and late binding [was Re: what does 'a=b=c=[]' do] Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-12-24 08:26 +0000
        Re: what does 'a=b=c=[]' do Ethan Furman <ethan@stoneleaf.us> - 2011-12-23 00:38 -0800
    Re: what does 'a=b=c=[]' do Ethan Furman <ethan@stoneleaf.us> - 2011-12-22 05:20 -0800
    Re: what does 'a=b=c=[]' do Eric <einazaki668@yahoo.com> - 2011-12-22 19:46 -0800
  Re: what does 'a=b=c=[]' do Lie Ryan <lie.1296@gmail.com> - 2011-12-24 21:30 +1100
  Re: what does 'a=b=c=[]' do Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2011-12-24 19:49 +0100

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