nem {maotai}

Negative Eigenvalue Magnitude

Description

Negative Eigenvalue Magnitude (NEM) is a measure of distortion for the data whether they are lying in Euclidean manner or not. When the value is exactly 0, it means the data is Euclidean. On the other hand, when NEM is far away from 0, it means not Euclidean. The concept of NEM is closely related to the definiteness of a Gram matrix.

Usage

nem(data)

Arguments

data

an (n\times p) matrix whose rows are observations.

Value

a nonnegative NEM value.

References

Pękalska E, Harol A, Duin RPW, Spillmann B, Bunke H (2006). “Non-Euclidean or Non-Metric Measures Can Be Informative.” In Yeung D, Kwok JT, Fred A, Roli F, de Ridder D (eds.), Structural, Syntactic, and Statistical Pattern Recognition, 871–880. ISBN 978-3-540-37241-7.

Examples

## use simple example of iris dataset 
data(iris) 
mydat = as.matrix(iris[,1:4])

## calculate NEM
nem(mydat)