# Transfer ColorFunction from ListContourPlot to ListLIC-Plot

I would like to transfer the colors of a ListContourPlot to a ListLIC-Plot. I tried to interpolate the data of the ListContourPlot and use it as ColorFunction for the second plot but I couldn't get it to work properly, is there a better way to do this?

data1 = Table[Sin[i + j^2], {i, 0, 3, 0.1}, {j, 0, 3, 0.1}];
data2 = Table[{Sin[i + j^2], Cos[i + j^2]}, {i, 0, 3, 0.1}, {j, 0, 3, 0.1}];
f = ListInterpolation[data1];
ListContourPlot[data1, ColorFunction -> "DarkRainbow"]
ListLineIntegralConvolutionPlot[data2, ColorFunction -> Function[{x, y, vx, vy, n},
ColorData["DarkRainbow"][f[x, y]]], RasterSize -> 100]


I get the following error:

InterpolatingFunction::dmval: Input value {0.,0.} lies outside the range of
data in the interpolating function. Extrapolation will be used. >>
...


The result should look remotely like the following • hat do you mean by "transfer the colors"? – Dr. belisarius Jun 3 '14 at 2:01
• I would like to color the ListLIC-Plot exacly like the ContourPlot. Basically overlaying the ListLIC-Plot with the ContourPlot plot. I add an example. – paw Jun 3 '14 at 2:34

## 2 Answers

1. You need to set ColorFunctionScaling -> False, otherwise the $x$ and $y$ passed into your ColorFunction are rescaled to lie between 0 and 1 instead of having their original values.

2. There's a discrepancy between how ListContourPlot and ListLineIntegralConvolutionPlot interpret the dimensions of the input arrays as $x$ and $y$ coordinates. So to get the image you say you want, you have to use f[y, x] in the ColorFunction. Still, I think it's quite likely that the image you actually want is the one with f[x, y], because then the colours correspond to the $x$-component of the velocity field as one might expect from the definitions of data1 and data2.

3. Finally, we have to rescale f to a $[0,1]$ range manually, say using Rescale, before passing it into ColorData.

ListLineIntegralConvolutionPlot[data2,
ColorFunction -> Function[{x, y, vx, vy, n},
ColorData["DarkRainbow"][Rescale[f[y, x], {-1, 1}]]],
ColorFunctionScaling -> False, RasterSize -> 100] You still get InterpolationFunction::dmval warnings, but at least you get the desired plot.

P.S. The plot I think you actually want, with f[x, y] instead of f[y, x]: l1 = ListContourPlot[data1, ColorFunction -> "DarkRainbow", Frame -> False,
PlotRange -> {{1., 31.}, {1., 31.}}, ContourStyle -> None];
l2 = ListLineIntegralConvolutionPlot[data2, ColorFunction -> GrayLevel, Frame -> False,
PlotRange -> {{1., 31.}, {1., 31.}}];
ImageCompose[l2, {l1, .5}] 