org.grinvin.graphs

Class Graphs


public final class Graphs
extends java.lang.Object

Provides some basic helper methods for graphs.

Note that adjacency matrix, adjacency list and distance matrix can also be obtained from the graph bundle directory, which may cache their values.

Method Summary

static int[][]
adjacencyList(GraphView graph)
Returns the adjacency list representation for the given graph.
static boolean[][]
booleanAdjacencyMatrix(GraphView graph)
Returns a boolean adjacency matrix for the given graph.
static int[][]
distanceMatrix(GraphView graph)
Returns the distance matrix for the given graph.
static int[]
eccentricityList(GraphView graph)
Returns the list with eccentricities for the given graph.
static double[]
eigenValues(GraphView graph)
Returns the list of eigenvalues of the given graph.

Method Details

adjacencyList

public static int[][] adjacencyList(GraphView graph)
Returns the adjacency list representation for the given graph. The resulting array contains an array of neighbour indices for every vertex. The length of each array is exactly the valency of the corresponding vertex.

booleanAdjacencyMatrix

public static boolean[][] booleanAdjacencyMatrix(GraphView graph)
Returns a boolean adjacency matrix for the given graph. Row and column indices correspond to vertex indices. Entries are true when the corresponding vertices are adjacent (and different) and false otherwise. Note that the contents of this matrix are valid only for as long as the graph given as a parameter remains unaltered.

distanceMatrix

public static int[][] distanceMatrix(GraphView graph)
Returns the distance matrix for the given graph. Row and column indices correspond to vertex indices. Entries contains the distance between corresponding vertices or 0 when vertices are equal or belong to different components of the graph.

eccentricityList

public static int[] eccentricityList(GraphView graph)
Returns the list with eccentricities for the given graph. The resulting array contains an integer for every vertex. If the graph is disconnected the array will contain Integer.MAX_VALUE for every vertex.

eigenValues

public static double[] eigenValues(GraphView graph)
Returns the list of eigenvalues of the given graph. These are the eigenvalues of the adjacency matrix of the graph. The resulting array contains the eigenvalues in descending order. If an error occurs during the calculation an array with length 0 is returned.