Re: [ferret_users] polygon to mask country

["Ansley C. Manke" <ansley.b.manke@xxxxxxxx>]

Hi Nicolas,

As a check of your definition, does a plot of the points

  PLOT/VS/LINE xp, yp

show the outline of the boundary you want?

On 3/25/2019 4:18 AM, Nicolas Freychet wrote:
> Dear Ferret users,
>
> I'm trying to create a mask for a country, following this discussion: 
> https://www.pmel.noaa.gov/maillists/tmap/ferret_users/fu_2012/msg00019.html
>
> I managed to have a netcdf file with all lon/lat coordinate to define 
> a polygon of the country as in the discussion, but now I am not sure 
> how to apply it to mask my data.
> The pt_in_poly function 
> (https://ferret.pmel.noaa.gov/Ferret/documentation/users-guide/appendix-a-external-functions/pt_in_poly) 
> requires to define a table of xp/yp. I tried to do something like:
>
> let xp=LON[d=7,i=1:735178]
> let yp=LAT[d=7,i=1:735178]
> let mask = if pt_in_poly(Tmax[d=1,l=1],xp,yp) gt 0 then 1
>
> But it doesn't seem to work. I think it's the way I define xp/yp that 
> is wrong, but I don't know how to make a table {} from a coordinate. 
> Any idea?
>
> Cheers,
> Nico