gnuplot-info

[Gnuplot-info] Nonlinear color bar question

[Patrick A. <pat...@co...>]

Hello,

  I am struggling to make a plot with a nonlinear color bar. I want the colors themselves to be nonlinear rather than the tic marks. My detailed question is here:

https://stackoverflow.com/questions/79929626/how-to-make-a-nonlinear-color-bar

Any help is appreciated,
Patrick

Re: [Gnuplot-info] Nonlinear color bar question

[Patrick A. <pat...@co...>]

I don't understand how to do that. What I am looking for is a color bar similar to the "mag" palette from GMT:

https://docs.generic-mapping-tools.org/6.3/_images/GMT_App_M_1a.png
________________________________
From: DeForest, Craig E. <cra...@sw...>
Sent: Wednesday, April 22, 2026 10:46 AM
To: Patrick Alken <pat...@co...>; gnu...@li... <gnu...@li...>
Subject: Re: Nonlinear color bar question

[External email - use caution]

PDL::Gnuplot does this by generating an explicit color lookup table, from which gnuplot interpolates values.  You can always fall back on that brute-force approach.

Get Outlook for iOS<https://aka.ms/o0ukef>
________________________________
From: Patrick Alken via gnuplot-info <gnu...@li...>
Sent: Wednesday, April 22, 2026 8:43:17 AM
To: gnu...@li... <gnu...@li...>
Subject: [Gnuplot-info] Nonlinear color bar question

[EXTERNAL EMAIL]

Hello,

  I am struggling to make a plot with a nonlinear color bar. I want the colors themselves to be nonlinear rather than the tic marks. My detailed question is here:

https://stackoverflow.com/questions/79929626/how-to-make-a-nonlinear-color-bar

Any help is appreciated,
Patrick

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Re: [Gnuplot-info] Nonlinear color bar question

[Philipp K. J. <ph...@ja...>]

On Wed, 22 Apr 2026 14:43:17 +0000
Patrick Alken via gnuplot-info <gnu...@li...>
wrote:

For gradients:

set palette defined ( 0 "red", 0.1 "white", 1 "blue" )

For sharp transitions, double the position param:

set palette defined ( 0 "red", 0.1 "red", 0.1 "white", 0.2 "white", 0.2
"blue", 1 "blue" )

Either way:

plot "data" u 1:2:3 lc pal

Also check: 

test palette

Note: The positions w/in "set palette" are
relative, they do not (automatically) 
correspond to values from the plot range.

Also consider: 

set cbrange

Best,

		Ph.

> Hello,
> 
>   I am struggling to make a plot with a nonlinear color bar. I want
> the colors themselves to be nonlinear rather than the tic marks. My
> detailed question is here:
> 
> https://stackoverflow.com/questions/79929626/how-to-make-a-nonlinear-color-bar
> 
> Any help is appreciated,
> Patrick
> 
> _______________________________________________
> gnuplot-info mailing list
> gnu...@li...
> Membership management via:
> https://lists.sourceforge.net/lists/listinfo/gnuplot-info



-- 

Philipp K. Janert
www.janert.me