rel.verts.triCC {pcds} | R Documentation |
The indices of the CC
-vertex regions in a triangle
that contains the points in a give data set.
Description
Returns the indices of the vertices
whose regions contain the points in data set Xp
in
a triangle tri
=(A,B,C)
and vertex regions are based on the circumcenter CC
of tri
.
(see the plots in the example for illustrations).
The vertices of the triangle tri
are labeled as
1=A
, 2=B
, and 3=C
also
according to the row number the vertex is recorded in tri
.
If a point in Xp
is not inside tri
,
then the function yields NA
as output.
The corresponding vertex region is the polygon
whose interior points are closest to that vertex.
If tri
is equilateral triangle,
then CC
and CM
(center of mass) coincide.
See also (Ceyhan (2005, 2010)).
Usage
rel.verts.triCC(Xp, tri)
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 |
Value
A list
with two elements
rv |
Indices (i.e., a |
tri |
The vertices of the triangle,
where row number corresponds to the vertex index in |
Author(s)
Elvan Ceyhan
References
Ceyhan E (2005).
An Investigation of Proximity Catch Digraphs in Delaunay Tessellations, also available as technical monograph titled Proximity Catch Digraphs: Auxiliary Tools, Properties, and Applications.
Ph.D. thesis, The Johns Hopkins University, Baltimore, MD, 21218.
Ceyhan E (2010).
“Extension of One-Dimensional Proximity Regions to Higher Dimensions.”
Computational Geometry: Theory and Applications, 43(9), 721-748.
Ceyhan E (2012).
“An investigation of new graph invariants related to the domination number of random proximity catch digraphs.”
Methodology and Computing in Applied Probability, 14(2), 299-334.
See Also
rel.verts.triCM
, rel.verts.tri
,
and rel.verts.tri.nondegPE
Examples
A<-c(1,1); B<-c(2,0); C<-c(1.5,2);
Tr<-rbind(A,B,C);
P<-c(.4,.2)
rel.verts.triCC(P,Tr)
n<-20 #try also n<-40
set.seed(1)
Xp<-runif.tri(n,Tr)$g
rel.verts.triCC(Xp,Tr)
rel.verts.triCC(rbind(Xp,c(2,2)),Tr)
(rv<-rel.verts.triCC(Xp,Tr))
CC<-circumcenter.tri(Tr)
D1<-(B+C)/2; D2<-(A+C)/2; D3<-(A+B)/2;
Ds<-rbind(D1,D2,D3)
Xlim<-range(Tr[,1],Xp[,1],CC[1])
Ylim<-range(Tr[,2],Xp[,2],CC[2])
xd<-Xlim[2]-Xlim[1]
yd<-Ylim[2]-Ylim[1]
plot(Tr,pch=".",asp=1,xlab="",ylab="",
main="Scatterplot of data points \n and the CC-vertex regions",
axes=TRUE,xlim=Xlim+xd*c(-.05,.05),ylim=Ylim+yd*c(-.05,.05))
polygon(Tr)
points(Xp,pch=".",col=1)
L<-matrix(rep(CC,3),ncol=2,byrow=TRUE); R<-Ds
segments(L[,1], L[,2], R[,1], R[,2], lty = 2)
xc<-Tr[,1]
yc<-Tr[,2]
txt.str<-c("rv=1","rv=2","rv=3")
text(xc,yc,txt.str)
txt<-rbind(CC,Ds)
xc<-txt[,1]+c(.04,.04,-.03,0)
yc<-txt[,2]+c(-.07,.04,.06,-.08)
txt.str<-c("CC","D1","D2","D3")
text(xc,yc,txt.str)
text(Xp,labels=factor(rv$rv))