[Thread Prev][Thread Next][Index]

Re: [ferret_users] making a contour a variable



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



--
Paul Goddard
PhD Candidate
Department of Geosciences
University of Arizona


[Thread Prev][Thread Next][Index]
Contact Us
Dept of Commerce / NOAA / OAR / PMEL / Ferret

Privacy Policy | Disclaimer | Accessibility Statement