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MathGroup Archive 1996

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Re: select a range of elements from a nested list

  • To: mathgroup at
  • Subject: [mg5455] Re: [mg5387] select a range of elements from a nested list
  • From: Sherman Reed <Sherman.Reed at>
  • Date: Sat, 7 Dec 1996 00:26:33 -0500
  • Sender: owner-wri-mathgroup at

>At 07:50 PM 12/5/96 +0000, you wrote:
>>Hi MathGroup
>>Say you have a nested list like that {{x1,y1},{x2,y2},{x3,y3},...{xn,yn}}
>>basically containing X and Y values for a XY plot in each element. The X
>>values span a range from say 0 to 0.4 and you ONLY want to select the
>>elements (x,y values) from the list for which the x value spans say 0 to
>>0.3. BUT you don't want to COUNT the elements (visually on the screen) and
>>figure out the position at which the x value is just greater than 0.3 and
>>then subtract 1 from this position.
>>I still want do define the list by using
>>Table[list[[x,1]],list[[x,2]],{x, 1, ZZZ}]
>>here ZZZ means the number for which the x value <= 0.3, this number needs
>>to be found by MATHEMATICA!
>>I like to know if there is a general procedure to select elements from a
>>nested list based on the values of one member of the elements of that
>>nested list.
>>I hope I made myself clear enough to you all.
>>Thanks a lot.
>>Oliver Schurr
>>Department of Chemistry
>>Georgetown University
>>Washington, DC 20057
>Below is a 2.2.3 version of what you requested.  Take a look, and try it.
>I think it meets your specs.  If you want a 3.0 version, I will be glad
>to help.  If you want modifications, send me a note.  The last four lines
>are simply a test of the package, and of course, can be deleted.  If you
>have other needs, I will be glad to consider them.
>Sherman C. Reed
>AT&T-Bell Laboratories (Lucent Technologies), retired
>Sr. Lecturer and grad advisor, UTA-EE Department, retired
I forgot to include the Mma code in the first transmission, sorry.

(*A Notebook to create a short list of a two element list

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