nnspat (version 0.1.2)

Ninv: Vector of Shared NNs and Number of Reflexive NNs

Description

Returns the Qvec and R where \(Qvec=(Q_0,Q_1,\ldots)\) with \(Q_j\) is the number of points shared as a NN by \(j\) other points i.e., number of points that are NN of \(i\) points, for \(i=0,1,2,\ldots\) and R is the number of reflexive pairs where points A and B are reflexive iff they are NN to each other.

Usage

Ninv(x, is.ipd = TRUE, ...)

Value

Returns a list with two elements

Qvec

vector of \(Q_j\) values

R

number of reflexive points

Arguments

x

The IPD matrix (if is.ipd=TRUE) or a data set of points in matrix or data frame form where points correspond to the rows (if is.ipd = FALSE).

is.ipd

A logical parameter (default=TRUE). If TRUE, x is taken as the inter-point distance matrix, otherwise, x is taken as the data set with rows representing the data points.

...

are for further arguments, such as method and p, passed to the dist function.

Author

Elvan Ceyhan

See Also

Qval, Qvec, sharedNN, Rval, and QRval

Examples

#3D data points
n<-20  #or try sample(1:20,1)
Y<-matrix(runif(3*n),ncol=3)
ipd<-ipd.mat(Y)
W<-Wmat(ipd)
sharedNN(W)
Qvec(W)
Ninv(ipd)
Ninv(Y,is.ipd = FALSE)
Ninv(Y,is.ipd = FALSE,method="max")

#1D data points
n<-15
X<-as.matrix(runif(n))# need to be entered as a matrix with one column 
#(i.e., a column vector), hence X<-runif(n) would not work
ipd<-ipd.mat(X)
W<-Wmat(ipd)
sharedNN(W)
Qvec(W)
Ninv(ipd)

#with possible ties in the data
Y<-matrix(round(runif(30)*10),ncol=3)
ny<-nrow(Y)
ipd<-ipd.mat(Y)
W<-Wmat(ipd)
sharedNN(W)
Qvec(W)
Ninv(ipd)