| Re: Using VERT_COLORS=RGBA in PLOT()? [message #88572 is a reply to message #88570] |
Tue, 13 May 2014 13:41  |
dg86
Messages: 118
Registered: September 2012
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Senior Member |
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On Tuesday, May 13, 2014 1:52:48 PM UTC-4, Chris Torrence wrote:
> On Tuesday, May 13, 2014 10:27:55 AM UTC-6, David Grier wrote:
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>> Dear Folks,
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>> I am trying to create a scatter plot in IDL 8.3 (MacOS)
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>> whose symbols have different colors and alpha values.
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>> The documentation for plot() suggests that I should be able to pass a 4 x NPTS array of
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>> RGBA values to the VERT_COLORS property of plot(), where NPTS is the number of points in
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>> my data set. When I try this, IDL complains:
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>> % PLOT: Array subscript for PALETTE must have same size as source expression.
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>> Here's a minimal example:
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>> npts = 10
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>> a = findgen(2,npts)
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>> rgb = bytarr(3,npts)
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>> p1 = plot(a, vert_colors=rgb) ; works
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>> p2 = plot(a, vert_colors=rgba) ; doesn't work
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>> I'd be grateful for pointers on how to set the transparency of individual vertices
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>> in a plot.
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>> Many thanks,
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>> David
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> Hi David,
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> Looks like a bug. I'll go ahead and fix it. In the meantime, the workaround is to set the vert_colors after the plot has been created. You also need to set an rgb_table (this will also get fixed). Something like this:
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> npts = 10
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> a = findgen(2,npts)
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> rgba = bytarr(4,npts)
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> rgba[3,*] = 20b*bindgen(npts)
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> p2 = plot(a)
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> p2.rgb_table=0
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> p2.vert_colors=rgba
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> Thanks for catching this!
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> -Chris
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> ExelisVIS
This is perfect. Thanks for the fix!
TTFN,
David
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