ContourPlot Legend with colorbar for arbitrary contour values

Question

I have a ContourPlot in which I have specified the contour-values myself as Contours->{0.01, 0.05, 0.1, 0.2, 0.3}. I would like to get the corresponding contour-values to be shown in the color-bar in the Legend. How do I do this?

To get the max and min values, I am using the code in the following post which defines the reportColorRange[...] function: ShowLegend values .

Part of my question is answered by another post:
How can I label a ListDensityPlot with a color bar? , but probably this only works for a linear spacing of contours?

An example code is below.

Needs["PlotLegends`"]
{plTest, colors, range} = reportColorRange[
  ContourPlot[xv^2 + yv^2, {xv, 0, 1}, {yv, 0, 1}, 
    Contours -> {0.01, 0.05, 0.1, 0.2, 0.3}, ColorFunction -> "Rainbow"]];
LMin = range[[1]];  LMax = range[[2]];
ShowLegend[plTest, {ColorData["Rainbow"][1 - #1] &, 6, 
  ToString[Round[LMax, 0.01]], ToString[Round[LMin, 0.01]], 
  LegendPosition -> {0.6, 0}, BaseStyle -> {FontSize -> 14}}] 

I would like the 5 contour-values to appear in the Legend next to the "ticks" which are blank right now. I have left the max and min values shown right now, but I don't necessarily need them. It's sufficient (and probably better) to show only the contour values.

Thanks.

PS: This is also related to another post of mine: Mathematica 8: ContourPlot finding out max and min function values Sorry for the multiple posts, but I am still converging on what appearance I want for the plot and legend.

Answer 1

Make a mainPlot and a legendPlot and put them both down on one "piece of paper" using Inset. Use ColorFunction -> False and Rescale so that contours in both plots will have the same color. Specify the FrameTicks on the legendPlot to match the contours.

mainPlot = ContourPlot[xv^2 + yv^2, {xv, 0, 1}, {yv, 0, 1},
   Contours -> {0.01, 0.05, 0.1, 0.2, 0.3},
   ColorFunctionScaling -> False,
   ColorFunction -> (ColorData["Rainbow"][Rescale[#, {0, 0.3}]] &),
   PlotRange -> {{0, 1}, {0, 1}, {0, 0.3}},
   ImageSize -> 250];

legendPlot = ContourPlot[y, {x, 0, 0.01}, {y, 0, 0.3},
   Contours -> {0.01, 0.05, 0.1, 0.2, 0.3},
   ColorFunctionScaling -> False,
   ColorFunction -> (ColorData["Rainbow"][Rescale[#, {0, 0.3}]] &),
   AspectRatio -> 10,
   PlotRange -> {{0, 0.01}, {0, 0.3}, {0, 0.3}},
   FrameTicks -> {None, {0.01, 0.05, 0.1, 0.2, 0.3}, None, None},
   ImageSize -> 50];

Show[
 Graphics[Inset[mainPlot, {Left, Bottom}, {Left, Bottom}]],
 Graphics[
  Inset[legendPlot, {1.12, 0.15}, {Left, Bottom}, {0.17, Automatic}]],
 PlotRange -> {{0, 1.3}, {0, 1.1}},
 ImageSize -> 300]