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Groups > comp.lang.python > #30983

Re: Insert item before each element of a list

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On 10/8/2012 3:28 PM, mooremathewl@gmail.com wrote:
> What's the best way to accomplish this?  Am I over-complicating it?  My gut feeling is there is a better way than the following:
>
>>>> import itertools
>>>> x = [1, 2, 3]
>>>> y = list(itertools.chain.from_iterable(('insertme', x[i]) for i in range(len(x))))
>>>> y
> ['insertme', 1, 'insertme', 2, 'insertme', 3]

The straightforward, crystal-clear, old-fashioned way

 >>> lst = []
 >>> for item in [1,2,3]:
	lst.append('insert me')
	lst.append(item)

 >>> lst
['insert me', 1, 'insert me', 2, 'insert me', 3]

Paul Rubin's list(gfunc(prefix, lst)) is similar in execution.

-- 
Terry Jan Reedy

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Insert item before each element of a list mooremathewl@gmail.com - 2012-10-08 12:28 -0700
  Re: Insert item before each element of a list Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-08 13:42 -0600
  Re: Insert item before each element of a list MRAB <python@mrabarnett.plus.com> - 2012-10-08 20:43 +0100
  Re: Insert item before each element of a list Ian Kelly <ian.g.kelly@gmail.com> - 2012-10-08 14:04 -0600
  Re: Insert item before each element of a list Agon Hajdari <agonh@freenet.de> - 2012-10-08 22:12 +0200
  Re: Insert item before each element of a list Peter Otten <__peter__@web.de> - 2012-10-08 23:12 +0200
  RE: Insert item before each element of a list "Prasad, Ramit" <ramit.prasad@jpmorgan.com> - 2012-10-08 21:15 +0000
  Re: Insert item before each element of a list Agon Hajdari <agonh@freenet.de> - 2012-10-08 23:39 +0200
  RE: Insert item before each element of a list "Prasad, Ramit" <ramit.prasad@jpmorgan.com> - 2012-10-08 22:12 +0000
  Re: Insert item before each element of a list Paul Rubin <no.email@nospam.invalid> - 2012-10-08 15:24 -0700
  Re: Insert item before each element of a list Nobody <nobody@nowhere.com> - 2012-10-08 23:35 +0100
  Re: Insert item before each element of a list "Alex" <foo@email.invalid> - 2012-10-09 00:08 +0000
  Re: Insert item before each element of a list Terry Reedy <tjreedy@udel.edu> - 2012-10-08 21:58 -0400
    Re: Insert item before each element of a list Roy Smith <roy@panix.com> - 2012-10-08 22:06 -0400
      Re: Insert item before each element of a list rusi <rustompmody@gmail.com> - 2012-10-08 19:34 -0700
        Re: Insert item before each element of a list rusi <rustompmody@gmail.com> - 2012-10-08 19:39 -0700
          Re: Insert item before each element of a list Hans Mulder <hansmu@xs4all.nl> - 2012-10-12 00:21 +0200
            Re: Insert item before each element of a list Terry Reedy <tjreedy@udel.edu> - 2012-10-11 19:38 -0400
            Re: Insert item before each element of a list Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-12 02:16 +0000
        Re: Insert item before each element of a list Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2012-10-09 12:01 +0000
      Re: Insert item before each element of a list alex23 <wuwei23@gmail.com> - 2012-10-08 20:11 -0700
      Re: Insert item before each element of a list mooremathewl@gmail.com - 2012-10-09 07:03 -0700
  Re: Insert item before each element of a list Duncan Booth <duncan.booth@invalid.invalid> - 2012-10-09 11:40 +0000
    Re: Insert item before each element of a list Peter Otten <__peter__@web.de> - 2012-10-09 14:55 +0200

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