[R-sig-Geo] points-in-polygons calculation

[Anne Ghisla]

Hi all,

during a spatial analysis I need to compute a point-in-polygon
calculation, and I chose findPolys() in PBSmapping package.

For the moment the script is built as follows:
- import the polygon shapefile with rgdal
- import the point shapefile with PBSmapping
- nested for cycles that
  - isolate each polygon (or region) through a superkey on the
attributes in data slot. The selected element is a homerange. It's then
converted in a PolySet, for next step
  - finds which points fall inside the homerange with findPolys()
  - picks up a defined value among the attributes of points and computes
mean of all values of the selected points, then writes it in a new
column of the attribute table

Can the for cycle be based on a unique key like PolygonsID? Among the
methods for sp classes I didn't find it. I found functions like
getPolygonsIDSlot but they have not to be used directly.

Any suggestions?

thank you in advance

Anne Ghisla
Università degli Studi dell'Insubria, Varese
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