ArrayPlot coordinates scaling for overlays

• To: mathgroup at smc.vnet.net
• Subject: [mg109167] ArrayPlot coordinates scaling for overlays
• From: fd <fdimer at gmail.com>
• Date: Wed, 14 Apr 2010 23:13:25 -0400 (EDT)

```All

This seems a simple problem I not finding an easy solution.

I have a plot obtained from an ArrayPlot, for which the coordinates
are the indexes of the matrix being plotted; I want to overlay to this
plot some other plot, say, from DensityPlot. I have to tell
Mathematica that the bottom left corner of the ArrayPlot is {xi,yi}
and the upper right is {xf,yf}.

It would be nice as well to know how you could do this with a raster
image in general.

I was trying to use ListDensityPlot, but for the specific problem I
dealing with it is excruciatingly slow.

I'm also working to re-scale the FrameTicks by defining a new
ArrayPlot function, with limited success. Below the code I'm working
on.

Felipe

arrayPlotScale[array_List, {xmin_, xmax_}, {ymin_, ymax_}] :=
Module[{deltas =
Reverse[{ymax - ymin, xmax - xmin}/Dimensions[array]],
n = Dimensions[array] // Reverse},
ArrayPlot[array,
FrameTicks ->
Reverse[{Table[{i, xmin + i deltas[[1]] }, {i, 0, n[[1]], 20}],
Table[{n[[2]] - i, ymin + i deltas[[2]]}, {i, 0, n[[2]],
10}]}]]]

test = Table[i j, {i, 1, 100}, {j, 100, 1, -1}];

arrayPlotScale[test, {0, 16}, {0, 100}]

```

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