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Re: Plot colors [message #84984 is a reply to message #84967]

Thu, 20 June 2013 10:24

Michael Galloy
Messages: 1114
Registered: April 2006

Senior Member

On 6/20/13 12:59 AM, Mats Löfdahl wrote:
> What are your favorite colors for overplotting several data sets in the
> same diagram? (I'm assuming Coyote graphics here.) You'd want them to be
> easy to tell apart and to have a good and similar contrast against the
> (white) background.
>
> For two colors it's easy: red and blue.
>
> But already for three colors, if you add green you get something with
> less contrasty. And for more colors, if you add the complement colors
> cyan, magenta, and yellow, both yellow and cyan have the same problem.
> So then I usually inspect the color names in cgcolor and pick darker
> versions of the too light colors and some redder version of yellow. And
> if I need more than six I don't really know what to do...
>
> So, what is a good strategy? Do you have a good list that you always
> use, and truncate it to the needed length? Or do you start the list
> differently depending on how long it has to be? Has anybody written a
> function for this? Something like
>
> function plotcolors, index, Ncolors
>
>
> /Mats

This is what the qualitative color tables in the Brewer color tables are
for.

Checkout color tables 27-34 in the Brewer color tables (the second set
of color tables) on:

http://docs.idldev.com/mglib/vis/color/mg_loadct.html

To use one of these, say 27, just do:

mg_loadct, /brewer, 27

and then just use COLOR=0, COLOR=1, ... COLOR=11 (color table 27 has 12
values).

The Brewer color tables are included in IDL now, but they interpolated
intermediate values for the qualitative color tables, so you have to use
something like the following to get the 5th of the 12 values in a color
table:

COLOR=5 * 256 / 12

Mike
--
Michael Galloy
www.michaelgalloy.com
Modern IDL: A Guide to IDL Programming (http://modernidl.idldev.com)
Research Mathematician
Tech-X Corporation

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[Message index]

		Plot colors By: Mats Löfdahl on Wed, 19 June 2013 23:59
		Re: Plot colors By: David Fanning on Thu, 20 June 2013 05:28
		Re: Plot colors By: Mats Löfdahl on Thu, 20 June 2013 08:44
		Re: Plot colors By: David Fanning on Thu, 20 June 2013 08:52
		Re: Plot colors By: David Fanning on Thu, 20 June 2013 09:10
		Re: Plot colors By: Mark Piper on Thu, 20 June 2013 09:54
		Re: Plot colors By: David Fanning on Thu, 20 June 2013 09:55
		Re: Plot colors By: Jim Pendleton on Thu, 20 June 2013 20:22
		Re: Plot colors By: David Fanning on Thu, 20 June 2013 20:28
		Re: Plot colors By: Michael Galloy on Thu, 20 June 2013 10:24
		Re: Plot colors By: Mats Löfdahl on Thu, 20 June 2013 11:25
		Re: Plot colors By: allisonjaynes on Tue, 09 July 2013 15:56
		Re: Plot colors By: Chip Helms on Wed, 10 July 2013 10:24
		Re: Plot colors By: David Fanning on Wed, 10 July 2013 10:29

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