6 changed files with 205 additions and 341 deletions
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import java.util.Random; |
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import java.util.Set; |
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import java.util.Map; |
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import java.util.TreeMap; |
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import java.util.List; |
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import java.util.LinkedList; |
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import java.util.Arrays; |
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import java.io.File; |
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import java.io.PrintStream; |
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import com.google.common.graph.Network; |
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import com.google.common.graph.NetworkBuilder; |
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import com.google.common.graph.ImmutableNetwork; |
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import com.google.common.graph.MutableNetwork; |
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import com.google.common.graph.EndpointPair; |
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import java.lang.IllegalArgumentException; |
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/** Static class to generate random graphs. |
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* |
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* We are interested in profiling code as a function of |
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* number of nodes N and number of edges E, |
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* so this class takes arguments N and E. |
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*/ |
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public class RandomGraph { |
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private RandomGraph(){}; |
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public static ImmutableNetwork<Node,Edge> buildGraph(int nodes) throws IllegalArgumentException { |
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// If connectivity not specified, set it to 1.
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return buildGraph(nodes, (nodes*(nodes-1))/2); |
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} |
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public static ImmutableNetwork<Node,Edge> buildGraph(int nodes, double connectivity) throws IllegalArgumentException { |
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// If connectivity not specified, set it to 1.
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return buildGraph(nodes,(int)connectivity*(nodes*(nodes-1))/2); |
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} |
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public static ImmutableNetwork<Node,Edge> buildGraph(int N, int E) throws IllegalArgumentException { |
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Random r = new Random(150); |
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/** Make a NetworkBuilder object for an undirected network and call build(). |
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* |
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* https://github.com/google/guava/wiki/GraphsExplained#building-graph-instances
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* |
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* This will load an adjacency matrix from a file. |
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* |
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* nodes is the number of nodes on the graph. |
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* connectivity is a number between 0 (totally disconnected) and 1 (fully connected). |
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*/ |
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// MutableNetwork is an interface requiring a type for nodes and a type for edges
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MutableNetwork<Node,Edge> roads = NetworkBuilder.undirected().build(); |
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// Add nodes to graph
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List<Node> all_nodes = new LinkedList<Node>(); |
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for(int n=0; n<N; n++) { |
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Node thenode = new Node(n); |
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all_nodes.add(thenode); |
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roads.addNode(thenode); |
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} |
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// Adding random edges to graph
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// between n_i and n_j
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//
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// If i != j, and edges are single and symmetric,
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// N nodes have N! possible connections.
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//
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// start with a sequence enumerating all possible edges of the graph:
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// j = 1 ... N!
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// Now we can convert each enumeration to its corresponding pair
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//
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//
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class Pair { |
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int left; |
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int right; |
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public Pair(int left, int right) { |
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this.left = left; |
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this.right = right; |
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} |
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} |
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// Make 2 arrays:
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// one integers ix = 1 .. E
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// one pairs P(i,j), i != j
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// we will make all possible pairs,
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// then shuffle indexes to pick pairs at random.
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Pair[] all_edges = new Pair[(N*(N-1))/2]; |
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int[] index = new int[(N*(N-1))/2]; |
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int c = 0; |
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for(int i=0;i<N;i++){ |
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for(int j=i+1;j<N;j++){ |
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// make the pair and increment the index
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all_edges[c] = new Pair(i,j); |
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index[c] = c; |
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c++; |
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} |
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} |
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// mix up the pair indexes
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RandomArray.shuffle(index); |
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for(int e : index) { |
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Pair p = all_edges[e]; |
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// now we have our random pair.
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// create a random distance and add to the graph.
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int distance = 10 + r.nextInt(100); |
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Edge egg = new Edge(distance); |
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roads.addEdge(all_nodes.get(p.left),all_nodes.get(p.right),egg); |
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} |
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// freeze the network
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ImmutableNetwork<Node,Edge> frozen_roads = ImmutableNetwork.copyOf(roads); |
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return frozen_roads; |
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} |
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public static void toDot( ImmutableNetwork<Node,Edge> graph) { |
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String dot = "graph G{\n"; |
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dot += "\tratio = fill; node [shape = circle]; edge [dir=none];\n"; |
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int i = 0; |
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for(Node n : graph.nodes()) { |
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dot += "\t" + n.id + " [style=filled fillcolor=gray];\n"; |
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} |
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int j = 0; |
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for(Edge e : graph.edges()) { |
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EndpointPair<Node> pair = graph.incidentNodes(e); |
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Node left = pair.nodeU(); |
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Node right = pair.nodeV(); |
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dot += "\t" + left.id + " -- " + right.id + " [label = \"" + e.value + "\"];\n"; |
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} |
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dot += "}\n"; |
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try{ |
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PrintStream p = new PrintStream(new File("graphviz.dot")); |
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p.println(dot); |
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} catch(Exception e) { |
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// meh.
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} |
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} |
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} |
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/** Static class to shuffle an array. |
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* (That's Java for you.) |
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*/ |
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class RandomArray { |
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public static void shuffle(int[] arr) { |
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Random r = new Random(150); |
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for(int i=(arr.length-1); i>0; i--) { |
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int j = r.nextInt(i+1); |
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// swap arr[i] and arr[j]
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int temp = arr[i]; |
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arr[i] = arr[j]; |
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arr[j] = temp; |
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} |
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} |
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} |
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