Transformation to make Euclidean a distance matrix
This function computes the smallest positive constant that makes Euclidean a distance matrix and applies it.
cailliez(distmat, print = FALSE, tol = 1e-07, cor.zero = TRUE)
distmat |
an object of class |
print |
if TRUE, prints the eigenvalues of the matrix |
tol |
a tolerance threshold for zero |
cor.zero |
if TRUE, zero distances are not modified |
an object of class dist containing a Euclidean distance matrix.
Daniel Chessel
Stéphane Dray stephane.dray@univ-lyon1.fr
Cailliez, F. (1983) The analytical solution of the additive constant problem. Psychometrika, 48, 305–310.
Legendre, P. and Anderson, M.J. (1999) Distance-based redundancy analysis: testing multispecies responses in multifactorial ecological experiments. Ecological Monographs, 69, 1–24.
Legendre, P., and Legendre, L. (1998) Numerical ecology, 2nd English edition edition. Elsevier Science BV, Amsterdam.
data(capitales) d0 <- capitales$dist is.euclid(d0) # FALSE d1 <- cailliez(d0, TRUE) # Cailliez constant = 2429.87867 is.euclid(d1) # TRUE plot(d0, d1) abline(lm(unclass(d1)~unclass(d0))) print(coefficients(lm(unclass(d1)~unclass(d0))), dig = 8) # d1 = d + Cte is.euclid(d0 + 2428) # FALSE is.euclid(d0 + 2430) # TRUE the smallest constant
Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.