rel.verts.triM {pcds}

The alternative function for the indices of the M-vertex regions in a triangle that contains the points in a give data set

Description

An alternative function to the function rel.verts.tri when the center M is not the circumcenter falling outside the triangle. This function only works for a center M in the interior of the triangle, with the projections of M to the edges along the lines joining M to the vertices.

Usage

rel.verts.triM(Xp, tri, M)

Arguments

Xp

A set of 2D points representing the set of data points for which indices of the vertex regions containing them are to be determined.

tri

A 3 \times 2 matrix with each row representing a vertex of the triangle.

M

A 2D point in Cartesian coordinates or a 3D point in barycentric coordinates which serves as a center in the interior of the triangle tri.

Value

A list with two elements

rv

Indices of the vertices whose regions contains points in Xp.

tri

The vertices of the triangle, where row number corresponds to the vertex index in rv.

Author(s)

Elvan Ceyhan

References

There are no references for Rd macro ⁠\insertAllCites⁠ on this help page.

See Also

rel.verts.tri

Examples

A<-c(1,1); B<-c(2,0); C<-c(1.5,2);
Tr<-rbind(A,B,C);
M<-c(1.6,1.0)

P<-c(.4,.2)
rel.verts.triM(P,Tr,M)

n<-20  #try also n<-40
set.seed(1)
Xp<-runif.tri(n,Tr)$g

M<-c(1.6,1.0)  #try also M<-c(1.3,1.3)

(rv<-rel.verts.tri(Xp,Tr,M))
rel.verts.triM(rbind(Xp,c(2,2)),Tr,M)

Ds<-prj.cent2edges(Tr,M)

Xlim<-range(Tr[,1])
Ylim<-range(Tr[,2])
xd<-Xlim[2]-Xlim[1]
yd<-Ylim[2]-Ylim[1]

plot(Tr,pch=".",xlab="",ylab="",axes=TRUE,xlim=Xlim+xd*c(-.05,.05),ylim=Ylim+yd*c(-.05,.05))
polygon(Tr)
points(Xp,pch=".",col=1)
L<-rbind(M,M,M); R<-Ds
segments(L[,1], L[,2], R[,1], R[,2], lty = 2)

xc<-Tr[,1]+c(-.03,.05,.05)
yc<-Tr[,2]+c(-.06,.02,.05)
txt.str<-c("rv=1","rv=2","rv=3")
text(xc,yc,txt.str)

txt<-rbind(M,Ds)
xc<-txt[,1]+c(.02,.04,-.03,0)
yc<-txt[,2]+c(.07,.03,.05,-.07)
txt.str<-c("M","D1","D2","D3")
text(xc,yc,txt.str)
text(Xp,labels=factor(rv$rv))