[ncl-talk] How to separated regions on a large map?

[Erik J. Schaffernicht]

I have a 2d map where certain gridpoints have a values, all the rest are 
set to FillValue or Missing. The spatial structure of the points with 
values are not a-priori known.
Now, I look for a function/procedure  in NCL (or maybe in R or Python, 
if those are better suited) that can tell me all the points that are 
part of a region given that at the beginning of the algorithm I provide 
one gridpoint that should be member as well.

The closure or border of my region is defined by all the gridpoints that 
are FillValue or Missing and direct neighbours of the points valid 
values.  On the total map there might be several such separated regions, 
so it is important to know if that I only get the indices of the region 
that belongs to my initial given grid point.

Is there anything coded like this in NCL  (or R or Python) already?

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