pgirmess (version 1.6.9)

rwhatbufCat: Extract the contents of a SpatialPixelsDataFrame or a SpatialGridDataFrame of categorical values within various buffer sizes centred on spatial points

Description

Extract the contents of a SpatialPixelsDataFrame or a SpatialGridDataFrame of categorical values within various buffer sizes centred on points

Usage

rwhatbufCat(rast, sites, bufsizes, att=1)

Arguments

rast

object of class SpatialPixelsDataFrame or SpatialGridDataFrame to analyse

sites

object of class inheriting from SpatialPoints containing the points on which buffers must be centred

bufsizes

a vector of buffer radii, e.g. c(500, 1000, 1500)

att

column number of the attribute variable

Value

A dataframe, with the buffer size as first column, the site ID as second column. The other colums are the pixel frequency of each category

Details

This function generates a data.frame with the frequency of each category of a raster map within various radius buffers centred on spatial points.

See Also

over, rwhatbufNum, rwhatbufCat2

Examples

# NOT RUN {
# raster creation
library(sp)
data(meuse.grid)
coordinates(meuse.grid) = ~x+y
gridded(meuse.grid) = TRUE

# random selection of points within the raster area
mypoints<-spsample(meuse.grid,n=10,type="random") # random points are appx 10, see spsample doc
mypoints<-SpatialPointsDataFrame(coordinates(mypoints),data.frame(id=1:nrow(mypoints@coords)))

image(meuse.grid,att=4,col=c("red","green","blue")) # soil map
plot(mypoints,add=TRUE) # points
  # get the number of pixels of each category in each buffer
rwhatbufCat(meuse.grid,mypoints,c(500,1000),att=4) 

# }