mahalanobis {nexus}

Mahalanobis Distance

Description

Computes the squared Mahalanobis distance of all rows in x.

Usage

## S4 method for signature 'CompositionMatrix'
mahalanobis(x, center, cov, ..., robust = TRUE, method = c("mve", "mcd"))

## S4 method for signature 'ILR'
mahalanobis(x, center, cov, ..., robust = TRUE, method = c("mve", "mcd"))

Arguments

x

A CompositionMatrix or an ILR object.

center

A numeric vector giving the mean vector of the distribution. If missing, will be estimated from x.

cov

A numeric matrix giving the covariance of the distribution. If missing, will be estimated from x.

...

Extra parameters to be passed to MASS::cov.rob(). Only used if robust is TRUE.

robust

A logical scalar: should robust location and scatter estimation be used?

method

A character string specifying the method to be used. It must be one of "mve" (minimum volume ellipsoid) or "mcd" (minimum covariance determinant). Only used if robust is TRUE.

Value

A numeric vector.

Author(s)

N. Frerebeau

See Also

stats::mahalanobis()

Other statistics: aggregate(), covariance(), dist, margin(), mean(), metric_var(), quantile(), scale(), variation()

Examples

## Data from Aitchison 1986
data("hongite")

## Coerce to compositional data
coda <- as_composition(hongite)

## Mahalanobis distance
mahalanobis(coda)