[ncl-talk] issue with gsn_add_polygon

[Adam Herrington]

I'm attempting to compute a raw violin-type plot. This is similar to a box
plot, but I'm drawing a polygon around the pdf, and I close the polygon
through a mirror image (-1*probability). Then I rotate it so it's vertical,
and align it with the x-axis "id" of the box plot.

If you're not following, I don't blame you ... this is hard to describe.
Attached is my attempt at this that will hopefully clarify what I'm trying
to do.

**digression before I go on to details on my primary issue**
I'd like to experiment with an actual violin plot, with a smoothed kernel
density estimate of the distribution. The routine kde_n_test
<https://www.ncl.ucar.edu/Document/Functions/Built-in/kde_n_test.shtml> should
work, but the warnings on the ncl page say the function is under
construction. Is that the latest update for this function?
**end digression**

You'll notice for panels 2 and 3 there is a line pivoting from the bottom
of the pdf's to the (0,0) point on the plot. I'm having trouble tracking
down why this occurs and how to fix it. I'm going to copy-paste the
relevant portions of the code for one of the x-value id's.

  dx = 0.4d0 ;; x-depth of the pdf
  xvals = (/1.,2.,3.,4.,5.,6./) ;; case id
...
    pdfib = pdfx(ibdiff,nbins,optpdf)
    pdfib = pdfib/max(pdfib)

    xib = new( (/2*nbins/), "double")
    yib = new( (/2*nbins/), "double")

    xib(0:nbins-1) = xvals(n) - dx*pdfib
    xib(nbins:2*nbins-1) = xvals(n) + dx*pdfib(nbins-1:0)
    yib(0:nbins-1) = pdfib at bin_center
    yib(nbins:2*nbins-1) = pdfib at bin_center(nbins-1:0)

    pgstr = unique_string("dum")
    plot@$pgstr$ = gsn_add_polygon(wks,plot(0),xib,yib,respg)

I am pretty sure the xib and yib are a closed contour.. they go from
0:nbins-1 and then nbins:2*nbins-1 ... Would like to get another set of
eyes on this though

thanks,
Adam
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