### Description

`sHexDist`

is supposed to calculate euclidian distances between
each pair of hexagons/rectangles in a 2D grid of input "sTopol" or
"sMap" object. It returns a symmetric matrix containing pairwise
distances.

### Usage

sHexDist(sObj)

### Arguments

- sObj
- an object of class "sTopol" or "sInit" or "sMap"

### Value

`dist`

: a symmetric matrix of nHex x nHex, containing
pairwise distances, where nHex is the total number of
hexagons/rectanges in the grid

### Note

The return matrix has rows/columns ordered in the same order as the
"coord" matrix of the input object does.

### Examples

# 1) generate an iid normal random matrix of 100x10
data <- matrix( rnorm(100*10,mean=0,sd=1), nrow=100, ncol=10)
# 2) from this input matrix, determine nHex=5*sqrt(nrow(data))=50,
# but it returns nHex=61, via "sHexGrid(nHex=50)", to make sure a supra-hexagonal grid
sTopol <- sTopology(data=data, lattice="hexa", shape="suprahex")
# 3) initialise the codebook matrix using "uniform" method
sI <- sInitial(data=data, sTopol=sTopol, init="uniform")
# 4) calculate distances between hexagons/rectangles in a 2D grid based on different objects
# 4a) based on an object of class "sTopol"
dist <- sHexDist(sObj=sTopol)
# 4b) based on an object of class "sMap"
dist <- sHexDist(sObj=sI)