Determines if points are on the convex hull of a triangulation object
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.
on.convex.hull(tri.obj, x, y)
tri.obj |
object of class |
x |
vector of x-coordinates of points to locate |
y |
vector of y-coordinates of points to locate |
Logical vector.
A. Gebhardt
R. J. Renka (1996). Algorithm 751: TRIPACK: a constrained two-dimensional Delaunay triangulation package. ACM Transactions on Mathematical Software. 22, 1-8.
# example from TRIPACK:
data(tritest)
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:
data(quakes)
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])Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.