spatialEco (version 1.3-5)

sample.annulus: Sample annulus

Description

Creates sample points based on annulus with defined inner and outer radius

Usage

sample.annulus(x, r1, r2, n = 10, ...)

Arguments

x

sp SpatialPoints or SpatialPointsDataFrame class object

r1

Numeric value defining inner radius of annulus (in projection units)

r2

Numeric value defining outer radius of annulus (in projection units)

n

Number of samples

...

Additional arguments passed to spsample

Value

sp SpatialPointsataFrame OBJECT

Examples

# NOT RUN {
library(sp)
library(rgeos)
data(meuse)
coordinates(meuse) <- ~x+y
proj4string(meuse) <- CRS("+init=epsg:28992")
xy <- meuse[2,]

rs100 <- sample.annulus(xy, r1=50, r2=100, n = 50, type = "random")
rs200 <- sample.annulus(xy, r1=100, r2=200, n = 50, type = "random")

plot(rs200, pch=20, col="red")
  points(rs100, pch=20, col="blue")
  points(xy, pch=20, cex=2, col="black")
  box()
  legend("topright", legend=c("50-100m", "100-200m", "source"), 
         pch=c(20,20,20), col=c("blue","red","black"))

# }