Re: can't set explicit colours

Hi Katja,

You didn't say how you wanted to choose the colors that you use. The "GetFillColors" function uses an array of contour levels and a scalar data field to determine a line color.

If this is not what you want, then exactly how do you want to select the colors?

You are on the right path with this loop:

> do j= 0,ntime-2
> pres@gsLineColor=GetFillColor(cnLevels,cmap,avg((/t(j),t(j+1)/)))
> gsn_polyline(wks,map,(/xpt(j),xpt(j+1)/),(/ypt(j),ypt(j+1)/),pres)
> end do

but you will need to set "pres@gsLineColor" yourself depending on what criteria you have.

If you look at example "annotate_4.ncl" at:

http://www.ncl.ucar.edu/Applications/traj.shtml

you will see that the lines are grouped based on what trajectory they are associated with, and then gsn_polyline is called multiple times, each time setting "gsLineColor" to something different. This example uses named colors ("black", "blue", "green", etc), rather than color index values (2, 5, 7, etc), which is the better method to use. If you use the Blue/Red color map and color index values, then you will only get various shades of red and blue. If you use named colors, then you will get those colors, regardless of what color map is currently associated with the workstation (note: this is only the case for NCL V6.1.0 and later).

--Mary

On Jun 21, 2013, at 5:10 AM, Katja Lohmüller <lohmueller@muk.uni-hannover.de> wrote:

> Hello NCL-talk,
>
> I'm drawing a trajectory of a flight and on its way, the trajectory
> should be coloured depending on the differnt temperatures which were
> taken along the flight. Now my problem is that NCL uses some haphazard
> colors of the RGB file ("BlWhRe") but I want to choose which colours
> should be used. So I tried different resources and functions but none
> I could find did work.(In my script the tries appear as commented
> lines) It would be great, if one of you will be able to help me with
> my problem.
>
> My script is as follows:
>
>
> ;*************************************************
> ; traj_2.ncl
> ;*************************************************
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_code.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/gsn_csm.ncl"
> load "$NCARG_ROOT/lib/ncarg/nclscripts/csm/contributed.ncl"
> ;**************************************************
> begin
> ;*************************************
> ; read in data
> ;************************************
> path = "/home/lohmueller/Desktop/BA/Amdardaten/Flutra01JanDLH_1.asc"
> data = asciiread(path,(/72,4/),"float")
> ; print(data)
> ntime=72
>
> ;********************************************
> wks = gsn_open_wks("pdf","trajectory") ; open workstation
> ;*********************************************
> ; color preps
> ;*****************************
>
> cnLevels=fspan(-55.0,5.0,13)
> gsn_define_colormap(wks,"BlWhRe")
> cmap = gsn_retrieve_colormap (wks)
> ; cmap=(/0.0,0.0,0.0/),(/1.0,1.0,1.0/),(/1.0,0.0,0.0/),(/0.0,1.0,0.0/),
> ; (/0.0,0.0,1.0/),(/1.0,1.0,0.0/),(/0.0,1.0,1.0/),(/1.0,0.0,1.0/),
> ; (/0.5,0.0,0.0/),(/0.5,1.0,1.0/),(/0.0,0.0,0.5/),(/1.0,1.0,0.5/),
> ; (/0.5,0.0,1.0/),(/1.0,0.5,0.0/),(/0.0,0.5,1.0/),(/0.5,1.0,0.0/),
> ; (/0.5,0.0,0.5/)
> gsn_define_colormap (wks,cmap)
>
> ;printVarSummary (cmap)
>
> res = True ; map resources
>
>
> res@gsnDraw = False ; don't draw
> res@gsnFrame = False ; don't advance frame
> res@vpWidthF = 0.90 ; make map bigger
> res@vpHeightF = 0.90
> res@mpMaxLatF = 55 ; select subregion
> res@mpMinLatF = 20
> res@mpMaxLonF = 65
> res@mpMinLonF = 5
> res@gsnMaximize = True
> res@gsnPaperOrientation = "landscape"
>
> ;res@cnFillColors = (/64,80,96/)
>
>
> ; label bar resources
> res_lb = True
> res_lb@vpWidthF = 0.60
> res_lb@vpHeightF = 0.10
> res_lb@lbPerimOn = False ; Turn off perimeter.
> res_lb@lbOrientation = "Horizontal" ; Default is vertical.
> res_lb@lbLabelStride = 2
> res_lb@lbLabelAlignment = "InteriorEdges" ; Default is "BoxCenters".
> res_lb@lbFillColors = (/"red","blue"/) ; Colors for boxes.
> res_lb@lbMonoFillPattern = True ; Fill them all solid.
> res_lb@lbLabelFontHeightF = 0.015
>
> res@tiMainString = "Trajektorie" ; title
>
> map = gsn_csm_map_ce(wks,res) ; create map
> delete(res)
> ;*********************************************
> ;trajectory parameters
> ;*********************************************
>
>
> xpt= new(ntime,float)
> ypt= new(ntime,float)
> t= new(ntime,float)
>
>
> ;*********************************************
> ;plot parameters
> ;*********************************************
>
> pres = True
> pres@gsLineThicknessF = 2.0
> ;pres@cnFillColors =(/2,8,14,20,25,31,37,42,48,55,61,67,68/)
> ;pres@gsLineColor =(/2,8,14,20,25,31,37,42,48,55,61,67,68/)
>
> mres = True
> first= True
> last= True
>
> ;*********************************************
>
> do i=0,ntime-1
> ypt(i) = data(i,0) ;extract latitude(Breite(N))
> xpt(i)= data(i,1) ;extract longitude(Länge(E))
> t(i) = data(i,3)
> end do
>
>
>
>
> draw(map)
>
>
> do j= 0,ntime-2
> pres@gsLineColor=GetFillColor(cnLevels,cmap,avg((/t(j),t(j+1)/)))
> gsn_polyline(wks,map,(/xpt(j),xpt(j+1)/),(/ypt(j),ypt(j+1)/),pres)
> end do
>
>
> ; create a unique marker to indicate the start of the trajectory
>
> first@gsMarkerSizeF = 20.0 ; marker size
> first@gsMarkerColor = "red" ; marker color
> last@gsMarkerSizeF = 9.0 ; marker size
> last@gsMarkerColor = "blue" ; marker color
>
> gsn_polymarker(wks,map,xpt(0),ypt(0),first) ;draw start of trajectory
> gsn_polymarker(wks,map,xpt(71),ypt(71),last) ;draw start of trajectory
> ;delete(first@gsMarkerColor)
> ;delete(first@gsMarkerSizeF)
>
>
>
> gsn_labelbar_ndc(wks,dimsizes(cnLevels)+1,cnLevels,0.20,0.20,res_lb)
> frame(wks)
> delete(wks)
>
>
>
> end
> --
> Katja Lohmüller
> Institut fuer Meteorologie und Klimatologie
> Leibniz Universitaet Hannover
> Herrenhaeuser Str. 2
> 30419 Hannover
>
> Email: lohmueller@muk.uni-hannover.de
> Mobil: 0049 176 61396963
> Buero: 0049 511 762 2396
>
>
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Received on Sun Jun 23 16:15:14 2013