checkmetric: Check for Metric Matrix
In maotai: Tools for Matrix Algebra, Optimization and Inference

Description Usage Arguments Value See Also Examples

This function checks whether the distance matrix D:=d_{ij} = d(x_i, x_j) satisfies four axioms to make itself a semimetric, which are (1) d_{ii} = 0, (2) d_{ij} > 0 for i\neq j, (3) d_{ij} = d_{ji}, and (4) d_{ij} ≤q d_{ik} + d_{kj}.

1	checkmetric(d)

`d`	`"dist"` object or (N\times N) matrix of pairwise distances.

a logical; TRUE if it satisfies metric property, FALSE otherwise.

checkdist

## Let's use L2 distance matrix of iris dataset
data(iris)
dx = as.matrix(stats::dist(iris[,1:4]))

# perturb d(i,j) 
dy = dx  
dy[1,2] <- dy[2,1] <- 10

# run the algorithm
checkmetric(dx)
checkmetric(dy)