simPts {DSpat} | R Documentation |
Generates a set of points from either a homogeneous or inhomogeneous Poisson process
with optional clustering. This is a wrapper function for rpoispp
from
the spatstat
package. The intensity is defined by covariates on a grid,
an intensity formula and parameters. The correlation structure is defined by the model
and the correlation parameters.
simPts(covariates,int.formula=~1, int.par=c(1), EN=100, model="exp", cor.par=NULL, showplot=FALSE, showpts=FALSE, ...)
covariates |
a matrix with columns x,y and any number of covariates x and y are the mid points of the grid cells; the order of the rows must match the formulation for function im |
int.formula |
formula for deriving expected intensity from covariates |
int.par |
parameters for intensity formula |
EN |
expected number of points |
model |
either "exp" or "gauss" for exponential or Gaussian correlation |
cor.par |
parameters controlling clustering of points cor.par[1]=sigma^2 cor.par[2]=alpha where cov(y1,y2)=sigma^2*exp(-d^p/alpha) and d is the distance between y1 and y2 and p=1 for exp and p=2 for gauss; if it is not specified then no additional clustering is included. |
showplot |
if TRUE, plot intensity and point process |
showpts |
if TRUE show points on the plot |
... |
parameters, if any, passed to plot |
ppp object of point locations
Devin Johnson; Jeff Laake
hab.range=30 probs=c(1/3,2/3) covariates = simCovariates(hab.range, probs) xpp=simPts(covariates=covariates,int.formula=~factor(habitat),int.par=c(0,1,2)) plot(xpp)