[ncl-talk] Reproducible gsn_add_poylline draw error [bug report]

[David Brown]

Hi Alan,
I will look into this.
 -dave

On Mon, May 22, 2017 at 3:36 PM, Alan Brammer <abrammer at albany.edu> wrote:

> Hey NCL devs,
>
> I’ve come across a sometimes avoidable but easily reproducible bug, that
> seems to still exist in 6.4.0
>
> Basically when a polyline is added to a plot with an axis on the order of
> time units (e.g. "hours since 1800”  or  > 1e6 ) and extends beyond the x
> limits of the plot,  it looks like the polyline function truncates the end
> of the lines erroneously.
> And then I just kind of broke it completely with the last plot.
>
> Couldn’t work out if the error is occurring in NhlAddPrimitive or in the
> create polytype section.
>
> Simple example script inline below with the output plots attached.
>
>
> Alan
>
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
>
> wks = gsn_open_wks("png","polyline_error")
>
> times := fspan(1881552, 1881984, 73)
> times at units = "hours since 1800-01-01"
>
> stime = times(8)
> ltime = times(50)
>
> res := True
> res at gsnDraw = False
> res at gsnFrame = False
> res at trXMinF = stime
> res at trXMaxF = ltime
>
> x := times
> y := sin(x) +4.
> res at trYMaxF = max(y)
> res at trYMinF = min(y)
>
> ;;;; .000001.png
> plot = gsn_csm_blank_plot(wks, res)
> line = gsn_add_polyline(wks, plot, x, y, False)
> draw(plot)
> frame(wks)
>
> ;;;; .000002.png
> res at trXMinF = stime
> res at trXMaxF = times(15)
> plot = gsn_csm_blank_plot(wks, res)
> line = gsn_add_polyline(wks, plot, x, y, False)
> draw(plot)
> frame(wks)
>
>
> ; oh jeez,   it gets worse.
> ;;;; .000003.png
> res at trYMinF = min(y)+0.00001    ;; trim just the very very bottom off the
> plot and watch all hell break lose.
> plot = gsn_csm_blank_plot(wks, res)
> line = gsn_add_polyline(wks, plot, x, y, False)
> draw(plot)
> frame(wks)
> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
>
>
>
>
>
>
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