on.convex.hull

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Percentile

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.

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
Value

• Logical vector.

References

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, convex.hull, in.convex.hull.

Aliases
• on.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])
Documentation reproduced from package tripack, version 1.0-1, License: R functions: GPL, Fortran code: available at netlib

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