Re: Problems with defintion of a ContourFunction

• To: mathgroup at christensen.cybernetics.net
• Subject: [mg1582] Re: Problems with defintion of a ContourFunction
• From: rubin at msu.edu (Paul A. Rubin)
• Date: Sat, 1 Jul 1995 03:58:10 -0400
• Organization: Michigan State University

In article <3sg3od\$8cq at news0.cybernetics.net>,
Martina Giarre <giarre at lgmhp3.epfl.ch> wrote:
->Hello,
->
->I have some problems in defining a ContourFunction. I cannot
->specify a color for a certain z-value in a ListContourPlot.
->
->I did some tests but the results are strange:
->
->
->test = Transpose[{{1,2,3,4,5,6},{1,2,3,4,5,6},
->		{1,2,3,4,5,6},{1,2,3,4,5,6},
->		{1,2,3,4,5,6},{1,2,3,4,5,6}}];
->
->g = {1,2,3,4,5,6};
->tc = Table[{Hue[d]},{d,0.4,1,0.1}];
->c[f_]:=While[f<=1,Hue[0.9]]
->ListContourPlot[test,	PlotRange->{1,6},
->			Contours->g,
->			ContourStyle->tc,
->			ContourLines->True,
->			ColorFunction->c];
->
->Unfortunately, this gives the chosen colors for the
->ContourLines but the ContourShading is not done in the
->right way. Instead of the intervall f<=1 being of the color
->Hue[0.9], all intervalls are of Hue[0.9].
->
->What is the mistake I do and how to solve the problem?
->
->
->Martina Giarre
->
The argument ListContourPlot sends to c is not the contour value but the
*scaled* contour value (domain 0 to 1).  Change f<=1 to f <= .2; this is
not exactly what you were proposing, but then values of the function less
than 1 will not plot if your smallest selected contour is 1.

You do not want While, by the way - it causes a loop.  Try

If[f<=.2,Hue[0.9],...]

where ... is replaced by the color you like for the other segments.

Paul

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* Paul A. Rubin                                  Phone: (517) 432-3509   *
* Department of Management                       Fax:   (517) 432-1111   *
* Eli Broad Graduate School of Management        Net:   RUBIN at MSU.EDU    *
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