nnspat (version 0.1.2)

NNdist: Distances between subjects and their NNs

Description

Returns the distances between subjects and their NNs. The output is an \(n \times 2\) matrix where \(n\) is the data size and first column is the subject index and second column contains the corresponding distances to NN subjects.

The argument is.ipd is a logical argument (default=TRUE) to determine the structure of the argument x. If TRUE, x is taken to be the inter-point distance (IPD) matrix, and if FALSE, x is taken to be the data set with rows representing the data points.

Usage

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

Value

Returns an \(n \times 2\) matrix where \(n\) is data size (i.e., number of subjects) and first column is the subject index and second column is the NN distances.

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

kthNNdist, kNNdist, and NNdist2cl

Examples

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

#1D data points
X<-as.matrix(runif(5)) # need to be entered as a matrix with one column
#(i.e., a column vector), hence X<-runif(5) would not work
ipd<-ipd.mat(X)
NNdist(ipd)
NNdist(X,is.ipd = FALSE)