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Re: colorbar question [message #79891 is a reply to message #79889]

Tue, 17 April 2012 11:00

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

zolile mtumela writes:

> My problem is that, we have values between(1 to 5 mHz) lets say
> (2.1, 2.3,2.5,2.9,3.3,4.2,..)that correspond to these cities/mag
> stations. Each and every city has their value. I want a different
> color for each city and display that color at the color with their
> value. With xyouts,...,color=220, displays one color in all cities on
> the map. I want different for these cities and also represent using
> color bar.

Yes. Color 220 is a *particular* color in the color table. It is
always the *same* color! Suppose your city colors range from 1.1 to 5.8.
You could scale these colors into the 256 values of the color table
by doing something like this:

minCityClr = 1.1
maxCityClr = 5.8
XYOuts, ..., Color=BytScl(cityColor, MIN=minCityClr, MAX=maxCityClr)

Now, your colors will look something like this:

Print, BytScl(2.1, MIN=minCityClr, MAX=maxCityClr)
54
Print, BytScl(2.3, MIN=minCityClr, MAX=maxCityClr)
65
Print, BytScl(2.5, MIN=minCityClr, MAX=maxCityClr)
76

This way, you are at the mercy of your color table. So
I wouldn't do it this way. I would probably just make
a vector of colors with the right number of colors:

cityColors = ['red', 'green', 'purple', ...]

And do it in a loop:

FOR j=0,numCities-1 DO cgText, city_lon[j], city_lat[j], $
city_name[j], Color=cityColors[j]

And, yeah, I'd be using Coyote Graphics routines. :-)

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: colorbar question By: David Fanning on Wed, 18 April 2012 05:13
		Re: colorbar question By: zolile mtumela on Wed, 18 April 2012 00:35
		Re: colorbar question By: David Fanning on Tue, 17 April 2012 11:40
		Re: colorbar question By: zolile mtumela on Tue, 17 April 2012 11:29
		Re: colorbar question By: David Fanning on Tue, 17 April 2012 11:00
		Re: colorbar question By: zolile mtumela on Tue, 17 April 2012 10:09
		Re: colorbar question By: David Fanning on Tue, 17 April 2012 05:56
		Re: colorbar question By: zolile mtumela on Thu, 19 April 2012 23:38
		Re: colorbar question By: zolile mtumela on Wed, 02 May 2012 06:43

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