Determines if points are on the convex hull of a triangulation object
Usage
on.convex.hull(tri.obj, x, y)
Arguments
tri.obj
|
object of class "tri"
|
x
|
vector of x-coordinates of points to locate
|
y
|
vector of y-coordinates of points to locate
|
Description
Given a triangulation tri.obj
of n points in the plane, this
subroutine returns a logical vector indicating if the points
(x_i,y_i)
lay on the convex hull of tri.obj
.Value
Logical vector.Author(s)
A. GebhardtReferences
R. J. Renka (1996). Algorithm 751: TRIPACK: a constrained
two-dimensional {Delaunay} triangulation package.
ACM Transactions on Mathematical Software.
22, 1-8.See Also
tri
, print.tri
, plot.tri
,
summary.tri
, triangles
,
add.constraint
, convex.hull
, in.convex.hull
.Examples
# example from TRIPACK:
tr<-tri.mesh(tritest$x,tritest$y)
on.convex.hull(tr,0.5,0.5)
on.convex.hull(tr,c(0.5,-1,1),c(0.5,1,1))
# use a part of the quakes data set:
quakes.part<-quakes[(quakes[,1]<=-10.78 & quakes[,1]>=-19.4 &
quakes[,2]<=182.29 & quakes[,2]>=165.77),]
q.tri<-tri.mesh(quakes.part$lon, quakes.part$lat, duplicate="remove")
on.convex.hull(q.tri,quakes.part$lon[1:20],quakes.part$lat[1:20])