[R] convert Map shapes to logical matrices - for set operations
James Muller
james.muller at canberra.net.au
Mon Dec 6 19:13:31 CET 2004
Hi, I have a little problem.
I'm trying to do the following:
Convert _projected_ shapes from a Map object into logical matrices.
That is, rasterize a shape into a logical "in-the-shape" and
"out-of-the-shape" matrix.
What I'm trying to do is get an 'equal-area' estimate of the area of
intersection between two overlapping shapes, without any concern about
there being holes in the shapes. I know owin can deal with most of this,
but for sure it doesn't support geographic projections, which will allow
the 'equal-area' estimate to be equal.
An idea I had was to pipe the output of the maptools Map plotting
function map into the matrix. But I really have no idea how to do that
at this point in my R education.
Any suggestions are extremely welcome.
Cheers,
James
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