Hi Paul,
here an example that may work for you:
Define an area that is one and zero:
yes? use coads_climatology
yes? set region/ l=1
yes? let mask= if sst gt 15 then 1 else 0
Now define the left, lower, and right and upper derivative:
yes? let mxp = mask[x=@ddf]
yes? let myp = mask[y=@ddf]
yes? let mxm = mask[x=@ddb]
yes? let mym = mask[y=@ddb]
Make a plot. If you are not familiar with the derivatives, please consult the manual.
Now define the line, where the derivative is greater or smaller than 0:
yes? let line = if mxp gt 0 or myp gt 0 or mxm lt 0 or mym lt 0 then 1 else 1/0
This is the result:
yes? shade/l=1 mask
yes? shade/over/l=1/pal=black line
or
yes? shade sst
yes? shade/over/pal=black line
May be this is a good starting point to play with modifications. Other schemes for corner points?
Finally, in ferret there is a check whether or not a point is within a polygone. Please find details in the manual.
Best,
Martin
Am 19.07.2016 um 19:17 schrieb Paul Goddard:
Hello all,
I would like to define a variable which is of the line of grid points which separates two values of a mask (the end product would look like a contour line). I attached a picture of the mask. How could I "select" the grid points which lie in the 0 value region (the shelf) but are adjacent to the 1 value region (off shore). I would think using the @SHF would be helpful, any ideas?
Thank you in advance,
Paul
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Paul GoddardPhD Candidate
Department of GeosciencesUniversity of Arizona