processRanges: process ranges
Description
Each range (.shp file) is imported using readOGR, overlayed on the previously created canvas and the results are saved to the active project file.Usage
processRanges(Files, con, metadata)
Arguments
con
A valid sqlite connection.
metadata
A logical value. If TRUE ranges metadata: range area, median range centroid and range extents (min, max) are saved to metadata_ranges table
Warning
If there are thousands of range map polygons with complex geometries to be processed and/or the canvas resolution is relatively high this step is going to be time consuming. For example processing all amphibians of the world (5816 ranges, total 252 MB) using a grid of 0.25 deg (unnecessary high) resolution takes 544 minutes on a 64-bit machine with 4 GB of RAM running Windows Vista and R 2.10.0. However, once this step has been performed and the results saved to the database, the other operations are very fast.Details
The overlay is performed using overlay. If the overlay returns no results (the polygon is smaller than a grid cell) then the centroid of the range will snap to the nearest point and only one grid cell will be returned for that range.References
Hurlbert, AH; Jetz, W (2007) Species richness, hotspots, and the scale dependence of range maps in ecology and conservation, PNAS, 13384-13389