directlabels - utility.function - Positioning Method - edges.to.outside

Given a list of edges from the convex or alpha hull, and a list of cluster centers, calculate a point near to each cluster on the outside of the hull.

edges.to.outside <- function
### Given a list of edges from the convex or alpha hull, and a list of
### cluster centers, calculate a point near to each cluster on the
### outside of the hull.
(edges,centers,debug=FALSE,...){
  if(debug){
    with(centers,grid.points(x,y,pch="+",default.units="cm"))
    with(edges,grid.segments(x1,y1,x2,y2,default.units="cm"))
  }
  closepts <- gapply(centers,project.onto.segments,edges,debug=debug,...)
  closepts$vjust <- ifelse(closepts$y-centers$y>0,0,1)
  closepts$hjust <- ifelse(closepts$x-centers$x>0,0,1)
  r <- apply.method("big.boxes",closepts)
  r$x <- (r$right-r$left)/2+r$left
  r$y <- (r$top-r$bottom)/2+r$bottom
  r$hjust <- 0.5
  r$vjust <- 0.5
  r
}