makeBiconnectedPlanar {RBGL} | R Documentation

## makeBiconnectedPlanar

### Description

makeBiconnectedPlanar description

### Usage

    makeBiconnectedPlanar(g)

### Arguments

`g` | instance of class graphNEL from Bioconductor graph class

### Details

From

http://www.boost.org/doc/libs/1_49_0/libs/graph/doc/planar_graphs.html

An undirected graph is connected if, for any two vertices u and v, there's a path from u to v. An undirected graph is biconnected if it is connected and it remains connected even if any single vertex is removed. Finally, a planar graph is maximal planar (also called triangulated) if no additional edge (with the exception of self-loops and parallel edges) can be added to it without creating a non-planar graph. Any maximal planar simple graph on n > 2 vertices has exactly 3n - 6 edges and 2n - 4 faces, a consequence of Euler's formula. If a planar graph isn't connected, isn't biconnected, or isn't maximal planar, there is some set of edges that can be added to the graph to make it satisfy any of those three properties while preserving planarity. Many planar graph drawing algorithms make at least one of these three assumptions about the input graph, so there are functions in the Boost Graph Library that can help:

make_connected adds a minimal set of edges to an undirected graph to make it connected.

make_biconnected_planar adds a set of edges to a connected, undirected planar graph to make it biconnected while preserving planarity.

make_maximal_planar adds a set of edges to a biconnected, undirected planar graph to make it maximal planar.

The function documented here implements the second approach.

### Value

A list with two elements: 'Is planar' is a logical indicating achievement of planarity, and 'new graph', a graphNEL instance that is biconnected and planar.

### Author(s)

Li Long <li.long@isb-sib.ch>

### References

Boost Graph Library ( www.boost.org/libs/graph/doc/index.html )

The Boost Graph Library: User Guide and Reference Manual; by Jeremy G. Siek, Lie-Quan Lee, and Andrew Lumsdaine; (Addison-Wesley, Pearson Education Inc., 2002), xxiv+321pp. ISBN 0-201-72914-8

### Examples

    V <- LETTERS[1:11]
    g <- new("graphNEL", nodes=V, edgemode="undirected")
    g <- addEdge(V[1+0], V[1+1], g)
    g <- addEdge(V[1+2], V[3+1], g)
    g <- addEdge(V[1+3], V[0+1], g)
    g <- addEdge(V[1+3], V[4+1], g)
    g <- addEdge(V[1+4], V[5+1], g)
    g <- addEdge(V[1+5], V[3+1], g)
    g <- addEdge(V[1+5], V[6+1], g)
    g <- addEdge(V[1+6], V[7+1], g)
    g <- addEdge(V[1+7], V[8+1], g)
    g <- addEdge(V[1+8], V[5+1], g)
    g <- addEdge(V[1+8], V[9+1], g)
    g <- addEdge(V[1+0], V[10+1], g)

    x6 <- makeBiconnectedPlanar(g)
    x6

[Package RBGL version 1.70.0 Index]