# spatgraph: Compute the edges of a spatial graph In spatgraphs: Graph Edge Computations for Spatial Point Patterns

## Description

Given a spatial point pattern, we compute the edges of a graph (network) for a specified type of edge relationship.

## Usage

 1 2 spatgraph(x, type = "geometric", par = NULL, verbose = FALSE, maxR = 0, doDists = FALSE, preGraph = NULL)

## Arguments

 x Input point pattern object type Type of the graph par Parameter(s) for the graph verbose Print details maxR Maximum range for edges, helps in large patterns. doDists Precompute distances? Speeds up some graphs, takes up memory. preGraph Precomputed graph, taken as a super-graph

## Details

Several edge definitions are supported:

geometric

par=numeric>0. Geometric graph, par = connection radius.

knn

par=integer>0. k-nearest neighbours graph, par = k.

mass_geometric

Connect two points if ||x-y||<m(x). par=vector giving the m(x_i)'s

markcross

Connect two points if ||x-y||<m(x)+m(y). par = vector giving the m(x_i)'s

gabriel

Gabriel graph. Additional parameter for allowing par=k instead of 0 points in the circle.

MST

Minimal spanning tree.

SIG

Spheres of Influence.

RST

RNG

Relative neighbourhood graph

CCC

Class-Cover-Catch, par=factor vector of point types. The factor vector is converted to integers according to R's internal representation of factors, and the points with type 1 will be the target. Use relevel to change the target.

The parameter 'maxR' can be given to bring n^3 graphs closer to n^2. k-nearest neighbours will warn if maxR is too small (<k neighbours for some points), others, like RNG, don't so be careful.

Voronoi diagram aka Delaunay triangulation is not supported as other R-packages can do it, see. e.g. package 'deldir'.

## Examples

 1 2 3 4 5 6 7 8 # basic example x <- matrix(runif(50*2), ncol=2) g <- spatgraph(x, "knn", par=3) plot(g, x) # bigger example xb <- matrix(runif(5000*2), ncol=2) gb <- spatgraph(xb, "RNG", maxR=0.1)

spatgraphs documentation built on Dec. 14, 2017, 5:04 p.m.