With this functions raster values are extracted by various overlaying spatial points created within a polygon shapefile.

extract2(rr, pp, points = NA, samp.type = "regular", weight = F,
  narm = F, seed = 1, returnVals = F)

Arguments

rr

Raster object; raster image

pp

Spatial object; polygon file

points

integer; Number of SpatialPoints created in the Polygon

samp.type

character; Sampling technique for the Spatial Points generated as described in the spsample() function of the "sp" package

weight

boolean; Weighting image considering the underlaying rasters a differentweight in the extraction computation. This makes pixel partially located within a polygon less weighted. Input is T/F

narm

boolean; removes na values

seed

integer; applies the set.seed() function enabling the control over

returnVals

boolean; return all extracted values