| cailliez {ade4} | R Documentation |
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.
From the DistPCoa program of P. Legendre et M.J. Anderson
http://www.fas.umontreal.ca/BIOL/Casgrain/en/labo/distpcoa.html
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