Re: how to draw a circle wrapping a few points

From: Mary Haley <haley_at_nyahnyahspammersnyahnyah>
Date: Mon Jul 29 2013 - 15:59:31 MDT

There's no automatic function to draw a circle on a plot. The best way to do this currently is to use gsn_polyline or gsn_add_polyline. See the attached sample script.

You didn't say how you wanted to determine where to draw the circle and how big. I just used some dummy values in this example.

Note the circle is not perfectly round here. That's because the plot area that I'm drawing in has a range of 24 on the Y axis, and 21 on the X axis.

If you uncomment these lines, the circle will be perfectly round:

; res@trXMinF = xmin
; res@trXMaxF = xmax
; res@trYMinF = ymin
; res@trYMaxF = ymax


On Jul 27, 2013, at 4:47 PM, <> wrote:

> Dear NCLers,
> For several curves plotted by gsn_xy, I want to draw,say, an empty circle to
> wrap a few points in the former. I checked up with the ncl-talk archive, seems, to draw a marker of cycles can do this.
> However, that needs much tuning of the radius of the marker (circles, here) to do it.
> Are there any simpler methods in NCL to do this?
> Your help is appreciated.
> Best,
> Ting Lei
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Received on Mon Jul 29 15:59:45 2013

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