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MathGroup Archive 2000

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Re: Re: A Dead Thread? Re. Coloring ExtendGraphics ListContourPlot s...

  • To: mathgroup at smc.vnet.net
  • Subject: [mg22201] Re: [mg22162] Re: [mg19437] A Dead Thread? Re. Coloring ExtendGraphics ListContourPlot s...
  • From: Hartmut Wolf <hwolf at debis.com>
  • Date: Fri, 18 Feb 2000 02:34:37 -0500 (EST)
  • Organization: debis Systemhaus
  • References: <200002170623.BAA04319@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Mark Harder schrieb:
> 
>     I am trying to create contour plots for irregular data, and after some
> work, I downloaded the right ExtendGraphics package, derived from Tom Wickham-Jones'
> book.  I was able to get contour plots without color, but using the ColorFunction
> option did not work.  Experimenting with equally spaced data showed that I
> could get colored ListContourPlot-s with the v.3.0.1 built
> -in function, but that the ExtendGraphics version seems to ignore my ColorFunction
> option setting.  In searching the Archives of this group in MathSource, I came
> upon Laurence Lours' posting (see above) in which he describes
> the same problem (last Aug.), but there doesn't seem to be any response to
> his last posting.
>     Has anyone found a solution to this problem, or some sort of work-around?
> Unlike Laurence, I am using a Windows NT4.0 system, with Mathematica v3.0.1.
> Thanks,
> mark e. harder
> harderm at ucs.orst.edu

Hello Mark,

...I haven't tried this out, but having a look into TWJ's book pp. 480
it could work if you procceed as

(1) load  Needs["ExtendGraphics`TriangularInterpolate`"]

(2) generate the trangular interpolation function from your data
 
   fun = TriangularInterpolate[data]

(3) generate a regular array of new data

   new = Table[fun[x,y], {x,...},{y,...}]

(4) use _standard_ built-in ListContourPlot


Step (1)-(3) are nothing else but a interpolation problem. Mathematica
ListInterpolation doesn't work in that case, since it needs a not
neccessarily equally spaced but rectangular grid. If you can get a
different interpolation algorithm, or write your own from first
principles, you could also use that instead.

Kind regards, Hartmut


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