[R-sig-Geo] sampling a raster using sample points

[Stratford, Jeffrey]

Hi everyone,

Does anyone have any suggestions on sampling a raster (NLCD land cover
map, 30 m res) using circular buffers centered on 100+ sample points?

The NLCD map has classifications such as high density urban, medium
density urban, crop, etc.  The goal is to produce a data set with the
percent of each cover type for each point and relate this to biological
data (+/- blood parasites).  The next goal would be to extrapolate
parasitism probabilities throughout the landscape but that's a big next
step.  For now, I'd be happy to figure out how to extract data from the
NLCD map.

In the past I had been using raster calculator in ArcGIS/spatial analyst
but I would prefer to use open source software. I'm also a low-level
programmer - my specialty is the ecological side. 

Thanks,

Jeff

************************************
Dr. Jeffrey A. Stratford
Department of Health and Biological Sciences
84 W. South Street
Wilkes University, PA 18766
jeffrey.stratford at wilkes.edu
570-408-4761 (office)
570-332-2942 (cell)
http://web.wilkes.edu/jeffrey.stratford/
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