Return the convex hull of a triangulation object
Given a triangulation tri.obj of n points in the plane, this
subroutine returns two vectors containing the coordinates
of the nodes on the boundary of the convex hull.
convex.hull(tri.obj, plot.it=FALSE, add=FALSE,...)
tri.obj |
object of class |
plot.it |
logical, if |
add |
logical. if |
... |
additional plot arguments |
x |
x coordinates of boundary nodes. |
y |
y coordinates of boundary nodes. |
A. Gebhardt
R. J. Renka (1996). Algorithm 751: TRIPACK: a constrained two-dimensional Delaunay triangulation package. ACM Transactions on Mathematical Software. 22, 1-8.
# rather simple example from TRIPACK:
data(tritest)
tr<-tri.mesh(tritest$x,tritest$y)
convex.hull(tr,plot.it=TRUE)
# random points:
rand.tr<-tri.mesh(runif(10),runif(10))
plot(rand.tr)
rand.ch<-convex.hull(rand.tr, plot.it=TRUE, add=TRUE, col="red")
# use a part of the quakes data set:
data(quakes)
quakes.part<-quakes[(quakes[,1]<=-17 & quakes[,1]>=-19.0 &
quakes[,2]<=182.0 & quakes[,2]>=180.0),]
quakes.tri<-tri.mesh(quakes.part$lon, quakes.part$lat, duplicate="remove")
plot(quakes.tri)
convex.hull(quakes.tri, plot.it=TRUE, add=TRUE, col="red")Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.