RE: Extended ListContourPlot and ContourShading

*To*: mathgroup at smc.vnet.net*Subject*: [mg28574] RE: [mg28551] Extended ListContourPlot and ContourShading*From*: "David Park" <djmp at earthlink.net>*Date*: Sat, 28 Apr 2001 21:36:00 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

Alison, I believe that the ExtendGraphics ListContourPlot does not provide for shading when you use its features. There is probably a reason for this. Perhaps that it is much easier to generate the lines than the polygons. In any case, I think the following solution, which also uses ExtendGraphics may work. Needs["ExtendGraphics`TriangularInterpolate`"] The function in your example is just x y. Here is a set of data obtained by sampling at 1000 points. I added sample points at the four corners of the square just to force the range to be {{x,-1,1},{y,-1,1}}. If you are using experimental data, you will probably have to check for the minimun and maximum values of x and y and tailor your plot to those values. d2 = Join[ Module[{x, y}, Table[{x = Random[Real, {-1, 1}], y = Random[Real, {-1, 1}], x y}, {1000}]], Flatten[Outer[{#1, #2, #1 #2} &, {-1, 1}, {-1, 1}], 1]]; This generates a TriangularInterpolation function. d3 = TriangularInterpolate[d2] TriangularInterpolating[ <> ] Now, we generate an array of data with even spacings. This was rather slow. d4 = Table[d3[x, y], {x, -1, 1, 0.1}, {y, -1, 1, 0.1}]; Now, we can use the regular ListContourPlot with all its features. ListContourPlot[d4, ColorFunction -> Hue]; On the other hand, if your problem is really to make plots in the xy-plane of functions defined in polar coordinates, I would have better suggestions. David Park djmp at earthlink.net http://home.earthlink.net/~djmp/ > From: Alison Musgrave [mailto:stores at maths.tcd.ie] To: mathgroup at smc.vnet.net > > Hi, > > I have been using the ExtendGraphics`Contour` version > of ListContourPlot to generate contour plots from a > list of (x,y,z) irregularly space data points. ContourShading > does not appear to work with this extended option: try the example > in "Mathematica Graphics" pg 483, > > > Needs["ExtendGraphics`Contour`"] > > d1 = Flatten[ > Table[Table[{r Sin[t], r Cos[t], r^2 Cos[t] Sin[t]}, {t, 0, > 2Pi - 2Pi/(10r), 2Pi/(10r)}], {r, 10}], 1]; > > c = ListContourPlot[d1] > > > ContourShading -> True does not work. Nor does ColorFunction. > Please note that this is only a problem for data entered in > (x,y,z) format and NOT for data in array format (compare > ListContourPlot[Table[x^2 + y^2, {x, -2, 2, .1}, {y, -2, 2, .1}]]). > Any ideas? > > Many thanks, > Alison Musgrave > musgrava at tcd.ie > >