[ncl-talk] How to coincide zero with the white color of the colo bar with uneven numbering

[Dennis Shea]

These are not appropriate for what you want to do. Remove them.

  res at gsnSpreadColors  =  True
  res at gsnSpreadColorStart = -1
  res at gsnSpreadColorEnd  = 2

===
There are two common approaches. Both require use of the 'ExplicitLevels'

[1]
Indexing from a specific color table. For example:

http://www.ncl.ucar.edu/Document/Graphics/color_table_gallery.shtml#White-in-the-middle

   gsn_define_colormap(wks, "BlueWhiteOrangeRed")        ; user specified

  res at cnLevelSelectionMode = "ExplicitLevels"
  res at cnLevels             = fspan(-2, 1, 16)    ; 16 contour levels
                                                 ; 17 colors
  res at cnFillPalette        = (/ 2,10,18,26,34,42,50,58, 66, 74, 82, 90
\    ; blues
                              ,127 \             ; white [also, 0
                              ,146,162,194,242/) ; yellow, red

The above may not be quite what you want but it gives you the idea.

---
You can force 'white' (background color) into *any* color scheme. by using
index 0 which is the
background color (white)


[2]
Named colors.
The  following are not the -2 to 1 @ 0.2 you mentioned. They are for
unequally spaced contours
but you get the idea. This

  res at cnLevelSelectionMode = "ExplicitLevels"
  res at cnLevels             = (/0.1,1,2.5,5,10,15,20,25,50,75/) ;   ;
10 contour values
  res at cnFillPalette        = (/"Snow","PaleTurquoise","PaleGreen"\ ;
11 contour colors
                              ,"SeaGreen3" ,"Yellow","Orange"    \
                              ,"HotPink","Orange","HotPink","Red"\
                              ,"Violet", "Purple", "Brown"       /)



On Thu, Nov 13, 2014 at 5:43 AM, mamadoulamine.mbaye at ucad.edu.sn <
mamadoulamine.mbaye at ucad.edu.sn> wrote:

>  Hi Tirkey,
>
> You can use   res at cnFillColors   = (/put the numbers corresponding of the
> desired color:
>
>
> https://www.ncl.ucar.edu/Document/Graphics/ColorTables/BlueWhiteOrangeRed.shtml
> /)
>
> Each color should has a number
>
> Hope this helps!
>
> Mamadou,
>
> Regards
>
>
>
>
>
>
>  ------------------------------
> *De :* ncl-talk-bounces at ucar.edu <ncl-talk-bounces at ucar.edu> de la part
> de snehlata Tirkey <snehlata_tirkey at yahoo.com>
> *Envoyé :* jeudi 13 novembre 2014 04:24
> *À :* ncl-talk at ucar.edu
> *Objet :* [ncl-talk] How to coincide zero with the white color of the
> colo bar with uneven numbering
>
>   Hello NCL users,
>
>  I am trying to plot a color plot with a color bar of range -1 to 2 with
> an interval of 0.2 by using-
>
>    wks = gsn_open_wks("ps","MSE_0.5")
>   gsn_define_colormap(wks,"BlueWhiteOrangeRed")
>
>   res               =  True
>   res at gsnMaximize      =  True
>   res at gsnAddCyclic     =  False
>   res at cnFillOn           =  True
>   res at gsnSpreadColors  =  True
>   res at gsnSpreadColorStart = -1
>   res at gsnSpreadColorEnd  = 2
>   res at trXMinF        = 11
>   res at trXMaxF        = 27
>   res at cnLevelSelectionMode =  "ManualLevels"
>   res at cnLevelSpacingF    = 0.2
>   res at cnMinLevelValF   =  -1
>   res at cnMaxLevelValF    = 2
>
> I want '0' to coincide with the white of the bar but it is coinciding with
> the yellow. Please help.
>
>  Thanking in anticipation.
>
>   Yours sincerely,
> Snehlata Tirkey
> e-mail: snehlata_tirkey at yahoo.com
>
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