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Topic: Re: [mg5387] select a range of elements from a nested list
Replies: 0

 Sherman Reed Posts: 112 Registered: 12/7/04
Re: [mg5387] select a range of elements from a nested list
Posted: Dec 6, 1996 11:27 PM

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
>
>

Oliver,

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.

sincerely

Sherman C. Reed
AT&T-Bell Laboratories (Lucent Technologies), retired