[ncl-talk] animation: delete polyline from plot ?

[Karin Meier-Fleischer]

Hi Rick,

indeed this is what I want. Thanks for the hint!

I was thinking about drawing the map every time again but I rejected the 
idea because I have more than 100 flights at one time step. But I will 
give it a try now. ;-)

Have a nice weekend!

Karin


Am 21.05.16 um 17:41 schrieb Rick Brownrigg:
> Hi Karin,
>
> Rather than use gns_add_polyline, which associates the line with the 
> plot, what about gsn_polyline, which just graphically overlays the 
> line.  I think I was able to achieve something like what you are after 
> with the attached script. The essence of the drawing is this:
>
>   deltaLon = (lon2 - lon1) / 5.
>   deltaLat = (lat2 - lat1) / 5.
>   do i=0,4
>      draw(plot1)
>      gsn_polyline(wks, plot1, (/lon1+deltaLon*i, 
> lon1+deltaLon*(i+1)/),   \
>                              (/lat1+deltaLat*i, lat1+deltaLat*(i+1)/),   \
>                  pres)
>      frame(wks)
>   end do
>
> Hope that helps...
> Rick
>
> On Fri, May 20, 2016 at 3:50 PM, Karin Meier-Fleischer 
> <meier-fleischer at dkrz.de <mailto:meier-fleischer at dkrz.de>> wrote:
>
>     Hi,
>
>     is it possible to delete a polyline added to a simple map plot by
>     gsn_add_polyline after it was drawn?
>
>     I have flight trace data consisting of many segments per flight
>     which I
>     am animating segment by segment. This is not a problem. The idea
>     now is
>     to delete the first two segments after drawing 3 segments and
>     further on
>     to simulate a moving trace part to the end point (like a disappearing
>     trail).
>
>     The following snippet will cause an error:
>
>     do n=0,nsegemnts-1
>         str = unique_string("trace")
>         map@$str$ =
>     gsn_add_polyline(wks,map,(/x(n-1),x(n)/),(/y(n-1),y(n)/),pres)
>
>         if(n .gt. 2) then
>            trold0 = "trace"+(n-3)
>            trold1 = "trace"+(n-2)
>            delete([/map@$trold0$,map@$trold1$/])
>         end if
>
>     end do
>
>     warning:TransformPostDraw: tfPolyDrawList element 0 is invalid
>     warning:TransformPostDraw: tfPolyDrawList element 1 is invalid
>     warning:Attempt to reference attribute (trace1) which is undefined
>
>
>     Due to the huge number of segments I would want to 'switch' the first
>     segments off, if possible, and not to draw each single plot from
>     scratch
>     again for each flight .
>
>     Bye,
>     Karin
>
>     _______________________________________________
>     ncl-talk mailing list
>     ncl-talk at ucar.edu <mailto:ncl-talk at ucar.edu>
>     List instructions, subscriber options, unsubscribe:
>     http://mailman.ucar.edu/mailman/listinfo/ncl-talk
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.ucar.edu/pipermail/ncl-talk/attachments/20160521/fad84270/attachment.html