Re: question about country outline

From: Rick Brownrigg <brownrig_at_nyahnyahspammersnyahnyah>
Date: Thu Dec 09 2010 - 09:12:19 MST

Hi Shinn,

The trouble stems from the single call to:

   line_data = gsn_add_polyline(wks, map_data, mrb_lon, mrb_lat, lnres)

which will treat all the coordinates in mrb_lot/mrb_lat as a
continuous line. You want to draw the line segments that make up the
countries individually, as in shapefile_3.ncl. In particular, you
want to replace the above call with something like:
   segments = f->segments
   geometry = f->geometry
   segsDims = dimsizes(segments)
   geomDims = dimsizes(geometry)
   geom_segIndex = f@geom_segIndex
   geom_numSegs = f@geom_numSegs
   segs_xyzIndex = f@segs_xyzIndex
   segs_numPnts = f@segs_numPnts
   numFeatures = geomDims(0)
   lines = new(segsDims(0),graphic) ; array to hold polylines
   segNum = 0 ; Counter for adding polylines
   do i=0, numFeatures-1
      startSegment = geometry(i, geom_segIndex)
      numSegments = geometry(i, geom_numSegs)
      do seg=startSegment, startSegment+numSegments-1
         startPT = segments(seg, segs_xyzIndex)
         endPT = startPT + segments(seg, segs_numPnts) - 1
         lines(segNum) = gsn_add_polyline(wks, map_data,
mrb_lon(startPT:endPT), \
                                                      
mrb_lat(startPT:endPT), lnres)
         segNum = segNum + 1
      end do
   end do

Check out the discussion at the top of the shapefiles page if the
above code doesn't make sense. Hope that helps...
Rick

On Dec 9, 2010, at 2:00 AM, shinn wong wrote:

> Dear all,
> I've tried to plot the outline boundary of some countries using data
> obtained from DIVA-GIS. The code and the output file can be seen in
> the attachment. However, the output is quite different from that of
> example 4 in the shapefile example page. Does anyone know how can i
> just plot the outline of the country like those in example 4 instead
> of all the data points? How can i get the coordinate of the outline
> of the country? Many thanks.
> Shinn
> <
> aa1
> .ncl
> >
> <
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Received on Thu Dec 9 09:12:25 2010

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