R: Vector of Shared NNs and Number of Reflexive NNs

Ninv	R Documentation

Vector of Shared NNs and Number of Reflexive NNs

Description

Returns the Qvec and R where Qvec=(Q_0,Q_1,…) 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,… 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, ...)

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.

Value

Returns a list with two elements

`Qvec`	vector of Q_j values
`R`	number of reflexive points

Author(s)

Elvan Ceyhan

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)