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MathGroup Archive 2004

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Re: extracting a list to a list, help please

  • To: mathgroup at smc.vnet.net
  • Subject: [mg46181] Re: [mg46155] extracting a list to a list, help please
  • From: János Löbb <janos.lobb at yale.edu>
  • Date: Tue, 10 Feb 2004 00:05:51 -0500 (EST)
  • References: <200402091054.FAA20948@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

My newbie approach"

a = {{a1, b1, c1, d1}, {a2, b2, c2, d2}, {a3,
     b3, c3, d3}, {a4, b4, c4, d4}, {a5, b5, c5, d5}}

a[[All, {1, 2}]]
{{a1, b1}, {a2, b2}, {a3, b3}, {a4, b4}, {a5, b5}}

János
On Feb 9, 2004, at 5:54 AM, Serge wrote:

> Hello,
>
> I am a beginner in Mathematica and I have a rather simple question. I
> made some calculations that I need for an orbit and I have a list that
> look like this:
>
> mylist1 = {{a1,b1,c1,d1},{a2,b2,c2,d2},{a3,b3,c3,d3},etc}
>
> All I want to do is to make a list of the form
>
> mylist2 = {{a1,b1},{a2,b2},{a3,b3},etc}
>
> from the original list (mylist1),
>
> so that I can ListPlot those pairs of points (they represent x and y
> coordinates for some orbit). I am having trouble figuring out how to do
> this. I tried using the Table command but I couldn't get it into the
> above form. I would greatly appreciate if someone can help me out.
> Thanks so much.
>
> Best,
> Serge
>
>
----------------------------------------------------------
"A cyber virgin has never had intercourse outside of virtual reality, 
whereas a virtual virgin has never had intercourse with a real person 
even in virtual reality"

-Ray Kurzweil - "The age of spiritual machines"


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