nnspat (version 0.1.2)

ipd.mat.euc: Euclidean Interpoint Distance Matrix

Description

Returns the Euclidean interpoint distance (IPD) matrix of a given the set of points x and y using two for loops with the euc.dist function of the current package. If y is provided (default=NULL) it yields a matrix of Euclidean distances between the rows of x and rows of y, otherwise it provides a square matrix with \(i,j\)-th entry being the Euclidean distance between row \(i\) and row \(j\) of x. This function is different from the ipd.mat function in this package. ipd.mat returns the full distance matrix for a variety of distance metrics (including the Euclidean metric), while ipd.mat.euc uses the Euclidean distance metric only. ipd.mat.euc(X) and ipd.mat(X) yield the same output for a set of points X, as the default metric in ipd.mat is also "euclidean".

Usage

ipd.mat.euc(x, y = NULL)

Value

A distance matrix whose \(i,j\)-th entry is the Euclidean distance between row \(i\) of x and row \(j\) of y if y is provided, otherwise \(i,j\)-th entry is the Euclidean distance between rows \(i\) and \(j\) of x.

Arguments

x

A set of points in matrix or data frame form where points correspond to the rows.

y

A set of points in matrix or data frame form where points correspond to the rows (default=NULL).

Author

Elvan Ceyhan

See Also

dist, ipd.mat.euc, and dist.std.data

Examples

#3D data points
n<-3
X<-matrix(runif(3*n),ncol=3)
ipd.mat.euc(X)

n<-5
Y<-matrix(runif(3*n),ncol=3)
ipd.mat.euc(X,Y)
ipd.mat.euc(X[1,],Y)
ipd.mat.euc(c(.1,.2,.3),Y)
ipd.mat.euc(X[1,],Y[3,])

#1D data points
X<-as.matrix(runif(3)) # need to be entered as a matrix with one column
#(i.e., a column vector), hence X<-runif(3) would not work
ipd.mat.euc(X)

Y<-as.matrix(runif(5))
ipd.mat.euc(X,Y)
ipd.mat.euc(X[1,],Y)
ipd.mat.euc(X[1,],Y[3,])