pcds (version 0.1.4)

plotCSregsTri: The plot of the Central Similarity (CS) Proximity Regions for a 2D data set - one triangle case

Plots the points in and outside of the triangle tri and also the CS proximity regions which are also triangular for points inside the triangle tri with edge regions are based on the center of mass CM.

Description

Plots the points in and outside of the triangle tri and also the CS proximity regions for points in data set Xp.

CS proximity regions are defined with respect to the triangle tri with expansion parameter \(t>0\), so CS proximity regions are defined only for points inside the triangle tri.

Edge regions are based on center \(M=(m_1,m_2)\) in Cartesian coordinates or \(M=(\alpha,\beta,\gamma)\) in barycentric coordinates in the interior of the triangle tri; default is \(M=(1,1,1)\) i.e., the center of mass of tri.

See also (ceyhan:Phd-thesis,ceyhan:arc-density-CS,ceyhan:test2014;textualpcds).

Usage

plotCSregsTri(
  Xp,
  tri,
  t,
  M = c(1, 1, 1),
  asp = NA,
  main = "",
  xlab = "",
  ylab = "",
  xlim = NULL,
  ylim = NULL,
  ...
)

Value

Plot of the CS proximity regions for points inside the triangle tri

(and just the points outside tri)

Arguments

Xp

A set of 2D points for which CS proximity regions are constructed.

tri

Three 2D points, stacked row-wise, each row representing a vertex of the triangle.

t

A positive real number which serves as the expansion parameter in CS proximity region.

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; default is \(M=(1,1,1)\) i.e., the center of mass of tri.

asp

A numeric value, giving the aspect ratio \(y/x\) (default is NA), see the official help page for asp by typing "? asp".

main

An overall title for the plot (default="").

xlab, ylab

Titles for the \(x\) and \(y\) axes, respectively (default="" for both).

xlim, ylim

Two numeric vectors of length 2, giving the \(x\)- and \(y\)-coordinate ranges (default=NULL for both).

...

Additional plot parameters.

Author

Elvan Ceyhan

References

See Also

plotCSregsMT, plotASregsTri and plotPEregsTri,

Examples

A<-c(1,1); B<-c(2,0); C<-c(1.5,2);
Tr<-rbind(A,B,C);
n<-10

set.seed(1)
dat<-runif.tri(n,Tr)$g
dat<-matrix(dat,ncol=2)

M<-as.numeric(runif.tri(1,Tr)$g)  #try also M<-c(1.6,1.0)

t<-.5  #try also t<-2

dat<-matrix(dat,ncol=2)
Xlim<-range(Tr[,1],dat[,1])
Ylim<-range(Tr[,2],dat[,2])
xd<-Xlim[2]-Xlim[1]
yd<-Ylim[2]-Ylim[1]

plotCSregsTri(dat[4,],Tr,t,M)
plotCSregsTri(dat,Tr,t,M)

if (dimension(M)==3) {M<-bary2cart(M,Tr)}
#need to run this when M is given in barycentric coordinates
plotCSregsTri(dat,Tr,t,M,main="CS Proximity Regions with t=.5",
xlab="",ylab="",xlim=Xlim+xd*c(-.05,.05),ylim=Ylim+yd*c(-.05,.05))
L<-rbind(M,M,M); R<-Tr
segments(L[,1], L[,2], R[,1], R[,2], lty=2)

txt<-rbind(Tr,M)
xc<-txt[,1]+c(-.02,.03,.03,.03)
yc<-txt[,2]+c(.02,.02,.02,.07)
txt.str<-c("A","B","C","M")
text(xc,yc,txt.str)