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Re: List Question

  • To: mathgroup at smc.vnet.net
  • Subject: [mg67955] Re: List Question
  • From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
  • Date: Thu, 13 Jul 2006 06:55:42 -0400 (EDT)
  • Organization: The Open University, Milton Keynes, UK
  • References: <e92e03$ljm$1@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Simon Bale wrote:
> Hi,
> 
> I have a list with the following structure:
> 
> {{x1,y1},{x2,y2},{x3,y3,z3},{x4,y4}...}
> 
> As you can see some of the data points have three elements. I would
> like to remove these z elements so that the list has a structure
> {{x1,y1},{x2,y2},{x3,y3},{x4,y4}...}. I'm not sure how to achieve this
> so any
> help is greatly appreciated.
> 
> Regards, Simon Bale.
> 
Hi Simon,

A transformation rule [1] will do it. For instance

{{x1, y1}, {x2, y2}, {x3, y3, z3}, {x4, y4}} /. {a_, b_, c_} :> {a, b}

returns

{{x1, y1}, {x2, y2}, {x3, y3}, {x4, y4}}

Best regards,
Jean-Marc

[1] "Transformation Rules and Definitions", _The Mathematica Book 
Online_, http://documents.wolfram.com/mathematica/book/section-2.5


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