convex.hull {tripack} | R Documentation |
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 "tri" |
plot.it |
logical, if TRUE the convex hull of
tri.obj will be plotted. |
add |
logical. if TRUE (and plot.it=TRUE ), add to
a current plot. |
... |
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.
tri
, print.tri
, plot.tri
, summary.tri
, triangles
, add.constraint
.
# 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")