Re: Plotting map data

Try the attached script.

This is setup for a 1x1 offset grid. This is the "slow but clear"
version. It could be made faster via some array manipulations.

Variable: grid
Type: float
Total Size: 259200 bytes
            64800 values
Number of Dimensions: 2
Dimensions and sizes: [lat | 180] x [lon | 360]
Coordinates:
            lat: [-89.5..89.5]
            lon: [-179.5..179.5]
Number Of Attributes: 3
  units : ???
  long_name : whatever
  _FillValue : 1e+30
(0)
(0) whatever: min=1.46223 max=3.10375

Roberta Perkins wrote:
> Hello,
>
> I have a text file containing 3 columns of data: Longitude, Latitude and the
> their corresponding value.
> There are missing coordinate values but they are no included in the list. I want
> to be able to plot the data showing the gaps. If I do contour_map then
> everything gets filled in. It seems that the only way I can get around this is
> to manually put in the coordinates that have a missing value and assign a
> _FillValue attribute.
>
> Is there another way in NCL that I can plot the data on a map without having to
> include the missing values and just plot the coordinates that are listed?
>
> sample of my text file:
>
> -179.50 -83.50 2.06218422311191e+18
>
> -179.50 -82.50 2.20194218404584e+18
>
> -179.50 -81.50 2.13624203495919e+18
>
> -179.50 -80.50 1.92270691252096e+18
>
> -179.50 -79.50 1.97066905283356e+18
>
> -179.50 -77.50 1.87546962524897e+18
>
> -179.50 -76.50 1.73247078507269e+18
>
> -179.50 -75.50 1.69635004139386e+18
>
> -179.50 -74.50 3.10375392456632e+18
>
> -179.50 -71.50 1.83906513885069e+18
>
> -179.50 -70.50 1.94054532045052e+18
>
> -179.50 -69.50 1.86284145932606e+18
>
> -179.50 -68.50 1.89290891045765e+18
>
> -179.50 -67.50 1.65054741063768e+18
>
> -179.50 -52.50 1.84016698694068e+18
>
> -179.50 -51.50 1.86419956234479e+18
>
> -179.50 -50.50 1.79983511372746e+18
>
> -179.50 -49.50 1.84267036875869e+18
>
> -179.50 -48.50 1.7015316273787e+18
>
> -179.50 -47.50 1.64754931730665e+18
>
> -179.50 -46.50 1.46223171768628e+18
>
> -179.50 -39.50 1.7475926433674e+18
>
> -179.50 -38.50 1.70060666322184e+18
>
> Thank you,
> Roberta Perkins
>
> _______________________________________________
> ncl-talk mailing list
> ncl-talk_at_ucar.edu
> http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>

-- 
======================================================
Dennis J. Shea                  tel: 303-497-1361    |
P.O. Box 3000                   fax: 303-497-1333    |
Climate Analysis Section                             |
Climate & Global Dynamics Div.                       |
National Center for Atmospheric Research             |
Boulder, CO  80307                                   |
USA                        email: shea 'at' ucar.edu |
======================================================

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
  ftxt = "data.txt"
  npts = numAsciiRow(ftxt) ; number of rows
  print(npts)
  
  data = asciiread(ftxt, (/npts,3/), "float")
  LON = data(:,0) ; for clarity
  LAT = data(:,1)
  VAL = data(:,2)

  nlat = 180 ; target grid
  lat = latGlobeFo(nlat, "lat", "latitude", "degrees_north")
  mlon = 360
  lon = lonGlobeFo(mlon, "lon", "longitude", "degrees_east")
  lon = (/ lon - 180. /) ; subtract 180 from all values
  lon&lon = lon ; update coordinates

;;print(lat)
;;print(lon)

  grid = new ( (/nlat,mlon/), typeof(VAL), 1e30 )
  grid!0 = "lat"
  grid!1 = "lon"
  grid&lat = lat
  grid&lon = lon
  grid_at_long_name = "whatever"
  grid_at_units = "???"
                           ; slow but clear
  do n=0,npts-1
     ml = ind(lon.eq.LON(n))
     nl = ind(lat.eq.LAT(n))
     print(n+" ml="+ml+" nl="+nl+" VAL="+VAL(n))
     grid(nl,ml) = (/ VAL(n) /)
  end do

  scale = 1e18
  grid = grid/scale
  printVarSummary(grid)
  printMinMax(grid, True)
 
  wks = gsn_open_wks("x11","perkins")
  gsn_define_colormap(wks,"BlAqGrYeOrRe") ; choose colormap

  res = True ; plot mods desired
  res_at_cnFillOn = True ; turn on color fill
  res_at_cnFillMode = "RasterFill" ; Raster Mode
  res_at_cnLinesOn = False ; turn of contour lines
 ;res_at_cnLevelSpacingF = 0.5 ; contour spacing
  res_at_gsnSpreadColors = True ; use full range of color map
  res_at_lbLabelAutoStride = True

  plot = gsn_csm_contour_map_ce(wks,grid, res)
end

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Received on Fri Apr 25 2008 - 14:08:21 MDT