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Area of overlap between 2 polygons
2 messages · Ryan Briscoe Runquist, Rolf Turner
On 10/09/11 08:31, Ryan Briscoe Runquist wrote:
Dear All,
I am new to spatial analysis in R, and I wanted to know if anyone could help
me. I am interested in finding the area of overlap between the ranges of 2
species. I have downloaded herbarium record data for a genus of plants that
includes species names and the lat/long coordinates of the record. I would
like to be able to compute:
the minimum convex polygon for each species (I have been able to do this
with earth.poly{fossil}),
the area of that polygon (also obtainable through earth.poly{fossil}),
and the centroid coordinate of the polygon.
I would then like to take these polygons and determine the pairwise area of
overlap between all species combination and the distance between centroids.
I have not been able to find a function that will help me do this. Is there
a function for this type of analysis and what class of data do I need to
make this work. Thank you in advance for any assistance.
The undocumented functions overlap.owin() and overlap.xypolygon()
in the "spatstat" package should do what you want.
cheers,
Rolf Turner