| Re: colors and plot direct graphics function [message #82449] |
Fri, 14 December 2012 18:28  |
chris_torrence@NOSPAM
Messages: 528
Registered: March 2007
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Senior Member |
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On Friday, December 14, 2012 4:31:50 PM UTC-7, bing999 wrote:
> Hi,
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>
>
> I switched from idl 7 to 8.2 recently, and start using direct graphics
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> for plotting purposes.
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>
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> To plot in colors in idl 7, I used to do:
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> loadct,39
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> plot,x,y,color=250
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> for a red line.
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>
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> With direct graphics I can do:
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>
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> p=plot(x,y,AXIS_STYLE=0,$
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> XRANGE=[0,30],YRANGE=[0,30],color='red')
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>
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> But is there a way to load a color table and use a single number value
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> (e.g. 250 for red) for colors instead of a string with the plot
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> function?
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> I find it convenient to use that when you want to overplot many curves
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> of different colors in a for loop for instance.
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> I couldn't find this tip in the IDL help...
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>
>
> Thanks!
Hi bing999,
There are a couple of different ways. If you want all the colors to come from the same color table, then you could use rgb_table and vert_colors:
p = plot(randomu(seed,100), rgb_table=39, vert_colors=240)
If you just wanted to be able to choose colors using an index, you could use the !color system variable, like this:
for i=1,10 do p = plot(randomu(seed,100), color=!color.(i), /overplot)
Either way will work fine. Probably the first way gives you the most control, since you can pick say every 20th color from a color table.
Just as an aside, be sure to check out the new Color Brewer color tables that we added to IDL 8.2.1:
http://www.exelisvis.com/docs/LoadingDefaultColorTables.html
Cheers,
Chris
ExelisVIS
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