Perhaps you're looking for something along the lines of Sobol sequences - refer Section 7.7 of Numerical Recipes in C by Press et al.
Sean On 18/05/06, Ben Bolker <[EMAIL PROTECTED]> wrote: > Beutel, Terry S <Terry.Beutel <at> dpi.qld.gov.au> writes: > > > > > I am trying to generate two dimensional random coordinates. > > > > For randomly distributed data I have simply used > > > > >xy<-cbind(runif(100),runif(100)) > > > > However I also want to generate coordinates that are more uniformly > > distributed, and coordinates that are more contagiously distributed than > > the above. > > > > > > here are some pictures I made for a talk recently, using > the Poisson cluster process function from "splancs" and > the Strauss process from "spatial" (I think) > > library(splancs) > library(spatial) > set.seed(1001) > sq <- as.matrix(data.frame(x=c(0,1,1,0,0),y=c(0,0,1,1,0))) > p.cl <- pcp.sim(rho=10,m=10,s2=0.001,region.poly=sq) > plot(p.cl) > n <- nrow(p.cl) > p.ran <- matrix(runif(2*n),nrow=n,dimnames=list(NULL,c("x","y"))) > ppregion() > p.reg <- Strauss(n,c=0.1,r=0.1) > p.reg <- matrix(c(p.reg$x,p.reg$y),nrow=n,dimnames=list(NULL,c("x","y"))) > all <- data.frame(rbind(p.cl,p.ran,p.reg), > tr=rep(c("clustered","random","regular"),each=n)) > library(lattice) > lattice.options(default.theme = ltheme) ## set as default > ltheme <- col.whitebg() > ltheme$xyplot.background$col <- "transparent" ## change strip bg > > trellis.par.set(theme=col.whitebg()) > print(xyplot(y~x|tr,data=all,layout=c(3,1),aspect="iso",scales=list(draw=FALSE), > bg="transparent",pch=16)) > > Ben Bolker > > ______________________________________________ > R-help@stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html > ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html