is.euclid: Is a Distance Matrix Euclidean ?

In ade4: Analysis of Ecological Data : Exploratory and Euclidean Methods in Environmental Sciences

Description

Confirmation of the Euclidean nature of a distance matrix by the Gower's theorem.
is.euclid is used in summary.dist.

Usage

is.euclid(distmat, plot = FALSE, print = FALSE, tol = 1e-07)
## S3 method for class 'dist'
summary(object, ...)

Arguments

distmat	an object of class 'dist'
plot	a logical value indicating whether the eigenvalues bar plot of the matrix of the term -1/2 dij² centred by rows and columns should be diplayed
print	a logical value indicating whether the eigenvalues of the matrix of the term -1/2 dij² centred by rows and columns should be printed
tol	a tolerance threshold : an eigenvalue is considered positive if it is larger than -tol*lambda1 where lambda1 is the largest eigenvalue.
object	an object of class 'dist'
...	further arguments passed to or from other methods

Value

returns a logical value indicating if all the eigenvalues are positive or equal to zero

Author(s)

Daniel Chessel
Stéphane Dray [e-mail]

References

Gower, J.C. and Legendre, P. (1986) Metric and Euclidean properties of dissimilarity coefficients. Journal of Classification, 3, 5–48.

Examples

w <- matrix(runif(10000), 100, 100)
w <- dist(w)
summary(w)
is.euclid (w) # TRUE
w <- quasieuclid(w) # no correction need in: quasieuclid(w)
w <- lingoes(w) # no correction need in: lingoes(w)
w <- cailliez(w) # no correction need in: cailliez(w)
rm(w)

Example output

Class: dist 
Distance matrix by lower triangle : d21, d22, ..., d2n, d32, ...
Size: 100 
Labels: 
call: dist(x = w)
method: euclidean 
Euclidean matrix (Gower 1966): TRUE 
[1] TRUE
Warning message:
In quasieuclid(w) : Euclidean distance found : no correction need
Warning message:
In lingoes(w) : Euclidean distance found : no correction need
Warning message:
In cailliez(w) : Euclidean distance found : no correction need

ade4 documentation built on May 2, 2019, 5:50 p.m.