| 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,
>
>
>
> I switched from idl 7 to 8.2 recently, and start using direct graphics
>
> for plotting purposes.
>
>
>
> To plot in colors in idl 7, I used to do:
>
> loadct,39
>
> plot,x,y,color=250
>
> for a red line.
>
>
>
> With direct graphics I can do:
>
>
>
> p=plot(x,y,AXIS_STYLE=0,$
>
> XRANGE=[0,30],YRANGE=[0,30],color='red')
>
>
>
> But is there a way to load a color table and use a single number value
>
> (e.g. 250 for red) for colors instead of a string with the plot
>
> function?
>
>
>
> I find it convenient to use that when you want to overplot many curves
>
> of different colors in a for loop for instance.
>
>
>
> I couldn't find this tip in the IDL help...
>
>
>
> 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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| Re: colors and plot direct graphics function [message #82451 is a reply to message #82449] |
Fri, 14 December 2012 15:57  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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bing999 writes:
> I switched from idl 7 to 8.2 recently, and start using direct graphics
> for plotting purposes.
>
> To plot in colors in idl 7, I used to do:
> loadct,39
> plot,x,y,color=250
> for a red line.
>
> With direct graphics I can do:
>
> p=plot(x,y,AXIS_STYLE=0,$
> XRANGE=[0,30],YRANGE=[0,30],color='red')
>
> But is there a way to load a color table and use a single number value
> (e.g. 250 for red) for colors instead of a string with the plot
> function?
>
> I find it convenient to use that when you want to overplot many curves
> of different colors in a for loop for instance.
>
> I couldn't find this tip in the IDL help...
It appears you have actually switched to function graphics,
which use the object graphics system, not the direct graphics
system.
If you wanted to stay with direct graphics, and still
have nearly all the advantages of a modern graphics
system, you could try Coyote Graphics:
http://www.idlcoyote.com/graphics_tips/coyote_graphics.php
With Coyote Graphics, you would do this to get an equivalent plot:
LoadCT, 39
cgPlot, cgDemoData(1), Color='250', XStyle=5, YStyle=5, /Window
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")
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