FW: [GMT-HELP] Fwd: How to make a non-symmetric color pallet around zero

Sorry I forgot the attachment

-----Original Message-----
From: basem elsaka [mailto:[email protected]] 
Sent: 15 January, 2014 9:21 AM
To: Help Mailing List ([email protected])
Subject: RE: [GMT-HELP] Fwd: How to make a non-symmetric color pallet around
zero

Hallo Walter, here is the same output
Nothing changed by multiplying the +ve values by 2.
The main problem as I think and addressed before is in psscale -B option. Is
there any solution to divide from -75 to 0 every 25 and divide 0 to 150
every 50 at the same time??? Then one can easily get symmetric scale around
zero, despite of different numbers.
I think it is a hard jop using GMT. Or not?
Basem

-----Original Message-----
From: Walter (HF) Smith [mailto:[email protected]]
Sent: 14 January, 2014 3:04 PM
To: [email protected]
Cc: [email protected]
Subject: Re: [GMT-HELP] Fwd: How to make a non-symmetric color pallet around
zero

Why can't you use makecpt to generate from -75 to +75 with steps of 25, and
then use awk to multiply the positive values by two?


On Jan 14, 2014, at 6:17 AM, basem elsaka wrote:

> Hallo Shahar,
> I have the same problem like you. I'm trying to make symmetric 
> colorbar from non-symmetric color scale As you can see in the attached 
> map, I'm trying to plot from -75 to zero every 25 spacing and from 0 
> to 150 every 50. My target is from -75 to 150 only 6 spacing (3 
> negative and 3 positive).
> There are mainly three problems:
> 1- as mentioned (symmetric spacing issue)
> 2- how to play with -B option in psscale to be -B25 and -B50 at the 
> same time ?? is there an option in psscale that is similar to -T in
makecpt?
> 3- how to make continuous colorbar in makecpt after appending the file 
> with -N option? Because as you see nobody can distinguish between 
> negative and positive values.
> Of course writing the following will lead to another color series (see 
> 2nd
> attachment)
> 
> makecpt -Z -Chaxby -T-75.0/0.0/25.0  -N > paletteTwice.cpt makecpt -Z 
> -Crainbow -T0.0/150.0/50.0 >> paletteTwice.cpt
> 
> So did you or anyone succeed to solve this problem. Anyone has 
> suggestions, pleeeeez
> 
> Basem
> Institute of Geodesy and Geoinformation, Bonn, Germany
> Currently: KACST, Saudi Arabia
> 
> 
> -----Original Message-----
> From: World-Wide GMT Usage and Help Mailing List 
> [mailto:[email protected]] On Behalf Of Paul Wessel
> Sent: 08 January, 2014 2:14 AM
> To: [email protected]
> Subject: [Bulk] Re: [GMT-HELP] Fwd: How to make a non-symmetric color 
> pallet around zero
> 
> In GMT5 see makecpt's new option -G for selecting just part of an 
> incoming cpt range.  You can then run makecpt twice; first for the 
> negative values and you stretch those via your -Tmin/0/inc and then 
> append the positive side stretched with -T0/max/inc, using -N during the
first call.
> in GMT4 you'll need to do some awking.
> 
> -p
> 
> On Jan 7, 2014, at 12:53 PM, Shahar Barak <[email protected]> wrote:
> 
>> Hi,
>> 
>> I'm trying to plot a figure that shows velocity perturbations by 
>> color (results of seismic tomography). I want values at zero and 
>> around zero to be white, but I don't want the color pallet to be 
>> symmetric. The minimum and maximum values are different.
>> In order to force white to be around zero I use grd2cpt with the -T 
>> option, however this forces the color pallet to be symmetric.
>> Any ideas on how to accomplish this? I need it to be automated, i.e, 
>> not by manually editing the CPT file.
>> 
>> Thanks,
>> 
>> Shahar
>> 
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> [email protected] <symmetric_scale.jpg><symmetric_scale_2.jpg>

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