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Re: lambda in list comprehension acting funny

From 88888 Dihedral <dihedral88888@googlemail.com>
Newsgroups comp.lang.python
Subject Re: lambda in list comprehension acting funny
Date 2012-07-11 20:39 -0700
Organization http://groups.google.com
Message-ID <62b4a584-42ca-4e10-af12-18b6f66eed76@googlegroups.com> (permalink)
References <mailman.2006.1341988919.4697.python-list@python.org> <jtjkng$ak6$1@theodyn.ncf.ca> <mailman.2014.1342024513.4697.python-list@python.org>

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On Thursday, July 12, 2012 12:34:33 AM UTC+8, Ian wrote:
> On Wed, Jul 11, 2012 at 4:28 AM, Colin J. Williams &lt;cjw@ncf.ca&gt; wrote:
> &gt; I don&#39;t understand why you would expect 1, 2, 4.
> 
> Because:
> 
> funcs[0](2) == 2 ** 0 == 1
> funcs[1](2) == 2 ** 1 == 2
> funcs[2](2) == 2 ** 2 == 4
> 
> &gt; Perhaps parentheses will help the order of evaluation:
> &gt;
> &gt; funcs = [(lambda x: x**i) for i in range( 5 )]
> &gt;
> &gt; This gives:
> &gt; 1
> &gt; 16
> &gt; 81
> 
> No, that gives 16, 16, 16 just like the original.  I don&#39;t understand
> why you would expect 1, 16, 81, unless you have misread the code.

I'll contribute my way of python programming:

def powerb(x, b): # 
     return x**b


One functor is enough!

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lambda in list comprehension acting funny Daniel Fetchinson <fetchinson@googlemail.com> - 2012-07-11 08:41 +0200
  Re: lambda in list comprehension acting funny "Colin J. Williams" <cjw@ncf.ca> - 2012-07-11 06:28 -0400
    Re: lambda in list comprehension acting funny Ian Kelly <ian.g.kelly@gmail.com> - 2012-07-11 10:34 -0600
      Re: lambda in list comprehension acting funny 88888 Dihedral <dihedral88888@googlemail.com> - 2012-07-11 20:39 -0700
        Re: lambda in list comprehension acting funny Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-12 03:51 +0000
          Re: lambda in list comprehension acting funny 88888 Dihedral <dihedral88888@googlemail.com> - 2012-07-11 22:04 -0700
            Re: lambda in list comprehension acting funny Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-12 06:18 +0000
              Re: lambda in list comprehension acting funny Mark Lawrence <breamoreboy@yahoo.co.uk> - 2012-07-12 08:40 +0100
      Re: lambda in list comprehension acting funny 88888 Dihedral <dihedral88888@googlemail.com> - 2012-07-11 20:39 -0700
  Re: lambda in list comprehension acting funny woooee <woooee@gmail.com> - 2012-07-11 11:38 -0700
    Re: lambda in list comprehension acting funny John Ladasky <john_ladasky@sbcglobal.net> - 2012-07-11 13:21 -0700
      Re: lambda in list comprehension acting funny Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-12 00:52 +0000
      Re: lambda in list comprehension acting funny Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-07-11 21:05 -0400
        Re: lambda in list comprehension acting funny Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-12 03:53 +0000
          Re: lambda in list comprehension acting funny Terry Reedy <tjreedy@udel.edu> - 2012-07-12 00:24 -0400
          Re: lambda in list comprehension acting funny Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-07-12 00:39 -0400
            Re: lambda in list comprehension acting funny Robert Miles <robertmiles@teranews.com> - 2012-08-15 19:26 -0500
      Re: lambda in list comprehension acting funny John O'Hagan <research@johnohagan.com> - 2012-07-12 15:29 +1000
      Re: lambda in list comprehension acting funny Robert Kern <robert.kern@gmail.com> - 2012-07-12 10:06 +0100
    Re: lambda in list comprehension acting funny Hans Mulder <hansmu@xs4all.nl> - 2012-07-12 00:22 +0200
    Re: lambda in list comprehension acting funny Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-11 23:47 +0000
      Re: lambda in list comprehension acting funny Daniel Fetchinson <fetchinson@googlemail.com> - 2012-07-12 04:54 +0200
  Re: lambda in list comprehension acting funny Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-12 03:59 +0000
    Re: lambda in list comprehension acting funny Ian Kelly <ian.g.kelly@gmail.com> - 2012-07-12 10:53 -0600
    Re: lambda in list comprehension acting funny Rotwang <sg552@hotmail.co.uk> - 2012-07-12 18:23 +0100
      Re: lambda in list comprehension acting funny Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-13 02:20 +0000
  Re: lambda in list comprehension acting funny rusi <rustompmody@gmail.com> - 2012-07-12 21:33 -0700
    Re: lambda in list comprehension acting funny Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-13 06:36 +0000
      Re: lambda in list comprehension acting funny rusi <rustompmody@gmail.com> - 2012-07-13 06:44 -0700
        Re: lambda in list comprehension acting funny rusi <rustompmody@gmail.com> - 2012-07-13 07:45 -0700
        RE: lambda in list comprehension acting funny "Prasad, Ramit" <ramit.prasad@jpmorgan.com> - 2012-07-13 16:12 +0000
          Re: lambda in list comprehension acting funny rusi <rustompmody@gmail.com> - 2012-07-13 09:46 -0700
            Re: lambda in list comprehension acting funny Chris Angelico <rosuav@gmail.com> - 2012-07-14 03:20 +1000
          Re: lambda in list comprehension acting funny Hans Mulder <hansmu@xs4all.nl> - 2012-07-13 19:53 +0200
            RE: lambda in list comprehension acting funny "Prasad, Ramit" <ramit.prasad@jpmorgan.com> - 2012-07-13 18:06 +0000
            Re: lambda in list comprehension acting funny Ian Kelly <ian.g.kelly@gmail.com> - 2012-07-13 12:54 -0600
              Re: lambda in list comprehension acting funny Hans Mulder <hansmu@xs4all.nl> - 2012-07-13 21:26 +0200
              Re: lambda in list comprehension acting funny Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-14 23:29 +0000
                Re: lambda in list comprehension acting funny Chris Angelico <rosuav@gmail.com> - 2012-07-15 10:49 +1000
                Re: lambda in list comprehension acting funny Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-15 08:32 +0000
                Re: lambda in list comprehension acting funny Chris Angelico <rosuav@gmail.com> - 2012-07-15 18:44 +1000
                Re: lambda in list comprehension acting funny Hans Mulder <hansmu@xs4all.nl> - 2012-07-15 21:25 +0200
                Re: lambda in list comprehension acting funny Terry Reedy <tjreedy@udel.edu> - 2012-07-15 06:27 -0400
            Re: lambda in list comprehension acting funny rusi <rustompmody@gmail.com> - 2012-07-13 19:31 -0700
              Re: lambda in list comprehension acting funny Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-14 03:43 +0000
                Re: lambda in list comprehension acting funny rusi <rustompmody@gmail.com> - 2012-07-13 21:53 -0700
                Re: lambda in list comprehension acting funny Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-07-14 07:46 +0000
        Re: lambda in list comprehension acting funny Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2012-07-13 13:47 -0400

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