/*
* Copyright (c) 2009, the JUNG Project and the Regents of the University
* of California
* All rights reserved.
*
* This software is open-source under the BSD license; see either
* "license.txt" or
* http://jung.sourceforge.net/license.txt for a description.
*/
package edu.uci.ics.jung.algorithms.generators;
import java.util.ArrayList;
import java.util.List;
import org.apache.commons.collections15.Factory;
import edu.uci.ics.jung.graph.Graph;
import edu.uci.ics.jung.graph.util.EdgeType;
/**
* Simple generator of an m x n lattice where each vertex is incident with each
* of its neighbors (to the left, right, up, and down). May be toroidal, in
* which case the vertices on the edges are connected to their counterparts on
* the opposite edges as well.
*
* <p>
* If the graph factory supplied has a default edge type of
* {@code EdgeType.DIRECTED}, then edges will be created in both directions
* between adjacent vertices.
*
* @author Joshua O'Madadhain
*/
public class Lattice2DGenerator<V, E> implements GraphGenerator<V, E> {
protected int row_count;
protected int col_count;
protected boolean is_toroidal;
protected boolean is_directed;
protected Factory<? extends Graph<V, E>> graph_factory;
protected Factory<V> vertex_factory;
protected Factory<E> edge_factory;
private List<V> v_array;
/**
* Constructs a generator of square lattices of size {@code latticeSize}
* with the specified parameters.
*
* @param graph_factory
* used to create the {@code Graph} for the lattice
* @param vertex_factory
* used to create the lattice vertices
* @param edge_factory
* used to create the lattice edges
* @param latticeSize
* the number of rows and columns of the lattice
* @param isToroidal
* if true, the created lattice wraps from top to bottom and left
* to right
*/
public Lattice2DGenerator(Factory<? extends Graph<V, E>> graph_factory,
Factory<V> vertex_factory, Factory<E> edge_factory, int latticeSize,
boolean isToroidal) {
this(graph_factory, vertex_factory, edge_factory, latticeSize,
latticeSize, isToroidal);
}
/**
* Creates a generator of {@code row_count} x {@code col_count} lattices
* with the specified parameters.
*
* @param graph_factory
* used to create the {@code Graph} for the lattice
* @param vertex_factory
* used to create the lattice vertices
* @param edge_factory
* used to create the lattice edges
* @param row_count
* the number of rows in the lattice
* @param col_count
* the number of columns in the lattice
* @param isToroidal
* if true, the created lattice wraps from top to bottom and left
* to right
*/
public Lattice2DGenerator(Factory<? extends Graph<V, E>> graph_factory,
Factory<V> vertex_factory, Factory<E> edge_factory, int row_count,
int col_count, boolean isToroidal) {
if (row_count < 2 || col_count < 2) {
throw new IllegalArgumentException(
"Row and column counts must each be at least 2.");
}
this.row_count = row_count;
this.col_count = col_count;
this.is_toroidal = isToroidal;
this.graph_factory = graph_factory;
this.vertex_factory = vertex_factory;
this.edge_factory = edge_factory;
this.is_directed = (graph_factory.create()
.getDefaultEdgeType() == EdgeType.DIRECTED);
}
/**
* @see edu.uci.ics.jung.algorithms.generators.GraphGenerator#create()
*/
@Override
public Graph<V, E> create() {
int vertex_count = row_count * col_count;
Graph<V, E> graph = graph_factory.create();
v_array = new ArrayList<V>(vertex_count);
for (int i = 0; i < vertex_count; i++) {
V v = vertex_factory.create();
graph.addVertex(v);
v_array.add(i, v);
}
int start = is_toroidal ? 0 : 1;
int end_row = is_toroidal ? row_count : row_count - 1;
int end_col = is_toroidal ? col_count : col_count - 1;
// fill in edges
// down
for (int i = 0; i < end_row; i++) {
for (int j = 0; j < col_count; j++) {
graph.addEdge(edge_factory.create(), getVertex(i, j),
getVertex(i + 1, j));
}
}
// right
for (int i = 0; i < row_count; i++) {
for (int j = 0; j < end_col; j++) {
graph.addEdge(edge_factory.create(), getVertex(i, j),
getVertex(i, j + 1));
}
}
// if the graph is directed, fill in the edges going the other
// direction...
if (graph.getDefaultEdgeType() == EdgeType.DIRECTED) {
// up
for (int i = start; i < row_count; i++) {
for (int j = 0; j < col_count; j++) {
graph.addEdge(edge_factory.create(), getVertex(i, j),
getVertex(i - 1, j));
}
}
// left
for (int i = 0; i < row_count; i++) {
for (int j = start; j < col_count; j++) {
graph.addEdge(edge_factory.create(), getVertex(i, j),
getVertex(i, j - 1));
}
}
}
return graph;
}
/**
* Returns the number of edges found in a lattice of this generator's
* specifications. (This is useful for subclasses that may modify the
* generated graphs to add more edges.)
*/
public int getGridEdgeCount() {
int boundary_adjustment = (is_toroidal ? 0 : 1);
int vertical_edge_count = col_count * (row_count - boundary_adjustment);
int horizontal_edge_count = row_count
* (col_count - boundary_adjustment);
return (vertical_edge_count + horizontal_edge_count)
* (is_directed ? 2 : 1);
}
protected int getIndex(int i, int j) {
return ((mod(i, row_count)) * col_count) + (mod(j, col_count));
}
protected int mod(int i, int modulus) {
int i_mod = i % modulus;
return i_mod >= 0 ? i_mod : i_mod + modulus;
}
/**
* Returns the vertex at position ({@code i mod row_count, j mod col_count}
* ).
*/
protected V getVertex(int i, int j) {
return v_array.get(getIndex(i, j));
}
/**
* Returns the {@code i}th vertex (counting row-wise).
*/
protected V getVertex(int i) {
return v_array.get(i);
}
/**
* Returns the row in which vertex {@code i} is found.
*/
protected int getRow(int i) {
return i / row_count;
}
/**
* Returns the column in which vertex {@code i} is found.
*/
protected int getCol(int i) {
return i % col_count;
}
}