R/legend.bubble.R

In mapplots: Data Visualisation on Maps

legend.bubble <-
function(x,y=NULL,z,maxradius=1,n=3,round=0,bty='o',mab=1.2,bg=NULL,inset=0,pch=21,pt.bg=NULL,txt.cex=1,txt.col=NULL,font=NULL,...){
  if(length(z)==1)
    legend <- round((seq(0,sqrt(z),length.out=n+1)^2)[-1],round) else
      legend <- round(sort(z),round)
  radius <- maxradius*sqrt(legend)/sqrt(max(legend)) 
  cex <- 2*radius/par('cxy')[2]/.375
  box <- legend.box(x,y,maxradius,mab,inset)
  if(bty=='o') rect(box[1],box[2],box[3],box[4],col=bg)
  x <- (box[1]+box[3])/2
  y <- box[2]-mab*maxradius+maxradius
  for(i in length(radius):1) {
    ri <- radius[i]
    cex <- 2*ri/par('cxy')[2]/.375  
    points(x,y-ri,cex=cex,pch=pch,bg=pt.bg,...)
    text(x,y-ri*2,legend[i],adj=c(0.5,-0.5),cex=txt.cex,col=txt.col,font=font)
  }
}