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

[snehlata Tirkey]

Thank you for all the help! I am getting the desired plot now.
Cheers, Yours sincerely,Snehlata Tirkeye-mail: snehlata_tirkey at yahoo.com 

     On Thursday, 13 November 2014, 21:13, Dennis Shea <shea at ucar.edu> wrote:
   

 A correction for [1]

                                               ; 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

should be

                                                 ; 17 colors
  res at cnFillColors        = (/ 2,10,18,26,34,42,50,58, 66, 74, 82, 90 \    ; blues
                              ,127 \             ; white [also, 0]
                              ,146,162,194,242/) ; yellow, red
========

Also, can can repeat index values. so -0.2, 0.0, 0.2  could be referenced to 127, 127,127   [or, 0,0,0]

On Thu, Nov 13, 2014 at 7:49 AM, Dennis Shea <shea at ucar.edu> wrote:

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, redThe 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 numberHope 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 Tirkeye-mail: snehlata_tirkey at yahoo.com
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