lingoes | R Documentation |
transforms a distance matrix in a Euclidean one.
lingoes(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 |
The function uses the smaller positive constant k which transforms the matrix of sqrt(dij² + 2*k) in an Euclidean one
returns an object of class dist
with a Euclidean distance
Daniel Chessel
Stéphane Dray stephane.dray@univ-lyon1.fr
Lingoes, J.C. (1971) Some boundary conditions for a monotone analysis of symmetric matrices. Psychometrika, 36, 195–203.
data(capitales) d0 <- capitales$dist is.euclid(d0) # FALSE d1 <- lingoes(d0, TRUE) # Lingoes constant = 2120982 is.euclid(d1) # TRUE plot(d0, d1) x0 <- sort(unclass(d0)) lines(x0, sqrt(x0^2 + 2 * 2120982), lwd = 3) is.euclid(sqrt(d0^2 + 2 * 2120981), tol = 1e-10) # FALSE is.euclid(sqrt(d0^2 + 2 * 2120982), tol = 1e-10) # FALSE is.euclid(sqrt(d0^2 + 2 * 2120983), tol = 1e-10) # TRUE the smaller constant
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