extract.data {SDMTools}R Documentation

Spatial Join of Points with Raster Grids

Description

extract.data extracts data from raster object of class 'asc' 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.

Usage

extract.data(pts,x)

Arguments

pts a two-column data frame with the x and y coordinates of the locations of interest.
x an object of class "asc" as defined in the adehabitat package

Details

Implements a faster version of 'join.asc' from the adehabitat package. NOTE: this assumes all locations are within the extent of the raster map.

Value

Returns a vector equal in length to the number of locations in pnts.

Author(s)

Jeremy VanDerWal jjvanderwal@gmail.com

Examples


#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)


[Package SDMTools version 1.0 Index]