extract.data {SDMTools} | R Documentation |
extract.data
extracts data from raster object of
class 'asc' (this and the adehabitat package),
'RasterLayer' (raster package) or 'SpatialGridDataFrame'
(sp package) at specified locations. This represents a
faster version of 'join.asc' of the adehabitat package that
assumes all locations are within the map extents.
Note: there is no interpolation done here. The
values reported are simply the values of the raster cell
the point falls into.
## S3 method for class 'data' extract(pts, x)
pts |
a two-column data frame or matrix with the x and y coordinates of the locations of interest. |
x |
a raster matrix of class 'asc' (this and the adehabitat package), 'RasterLayer' (raster package) or 'SpatialGridDataFrame' (sp package) |
Implements a faster version of 'join.asc' from the
adehabitat package.
NOTE: this assumes all
locations are within the extent of the raster map. Values
outside the extent will be given a value of NA.
Returns a vector equal in length to the number of locations in pnts.
Jeremy VanDerWal jjvanderwal@gmail.com
#create a simple object of class 'asc' tasc = as.asc(matrix(1:50,nr=50,nc=50)); print(tasc) #define some point locations points = data.frame(x=runif(25,1,50),y=runif(25,1,50)) #extract the data points$values = extract.data(points,tasc) #show the data print(points)