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package tutorials;
import smile.*;
// Tutorial6 creates a dynamic Bayesian network (DBN),
// performs the inference, then saves the model to disk.
public class Tutorial6 {
public static void run() {
System.out.println("Starting Tutorial6...");
Network net = new Network();
int loc = createCptNode(
net, "Location", "Location",
new String[] { "Pittsburgh", "Sahara" },
160, 360);
int rain = createCptNode(
net, "Rain", "Rain",
new String[] { "true", "false" },
380, 240);
int umb = createCptNode(
net, "Umbrella", "Umbrella",
new String[] { "true", "false" },
300, 100);
net.setNodeTemporalType(rain, Network.NodeTemporalType.PLATE);
net.setNodeTemporalType(umb, Network.NodeTemporalType.PLATE);
net.addArc(loc, rain);
net.addTemporalArc(rain, rain, 1);
net.addArc(rain, umb);
double[] rainDef = new double[] {
0.7, // P(Rain=true |Location=Pittsburgh)
0.3, // P(Rain=false|Location=Pittsburgh)
0.01, // P(Rain=true |Location=Sahara)
0.99 // P(Rain=false|Location=Sahara)
};
net.setNodeDefinition(rain, rainDef);
double[] rainDefTemporal = new double[] {
0.7, // P(Rain=true |Location=Pittsburgh,Rain[t-1]=true)
0.3, // P(Rain=false|Location=Pittsburgh,Rain[t-1]=true)
0.3, // P(Rain=true |Location=Pittsburgh,Rain[t-1]=false)
0.7, // P(Rain=false|Location=Pittsburgh,Rain[t-1]=false)
0.001, // P(Rain=true |Location=Sahara,Rain[t-1]=true)
0.999, // P(Rain=false|Location=Sahara,Rain[t-1]=true)
0.01, // P(Rain=true |Location=Sahara,Rain[t-1]=false)
0.99 // P(Rain=false|Location=Sahara,Rain[t-1]=false)
};
net.setNodeTemporalDefinition(rain, 1, rainDefTemporal);
double[] umbDef = new double[] {
0.9, // P(Umbrella=true |Rain=true)
0.1, // P(Umbrella=false|Rain=true)
0.2, // P(Umbrella=true |Rain=false)
0.8 // P(Umbrella=false|Rain=false)
};
net.setNodeDefinition(umb, umbDef);
net.setSliceCount(5);
System.out.println("Performing update without evidence.");
updateAndShowTemporalResults(net);
System.out.println(
"Setting Umbrella[t=1] to true and Umbrella[t=3] to false.");
net.setTemporalEvidence(umb, 1, 0);
net.setTemporalEvidence(umb, 3, 1);
updateAndShowTemporalResults(net);
net.writeFile("tutorial6.xdsl");
System.out.println(
"Tutorial6 complete: Network written to tutorial6.xdsl");
}
private static void updateAndShowTemporalResults(Network net) {
net.updateBeliefs();
int sliceCount = net.getSliceCount();
for (int h = net.getFirstNode(); h >= 0; h = net.getNextNode(h)) {
if (net.getNodeTemporalType(h) == Network.NodeTemporalType.PLATE) {
int outcomeCount = net.getOutcomeCount(h);
System.out.printf(
"Temporal beliefs for %s:\n", net.getNodeId(h));
double[] v = net.getNodeValue(h);
for (int sliceIdx = 0; sliceIdx < sliceCount; sliceIdx++) {
System.out.printf("\tt=%d:", sliceIdx);
for (int i = 0; i < outcomeCount; i++) {
System.out.printf(" %f", v[sliceIdx*outcomeCount+i]);
}
System.out.println();
}
}
}
System.out.println();
}
private static int createCptNode(
Network net, String id, String name,
String[] outcomes, int xPos, int yPos) {
int handle = net.addNode(Network.NodeType.CPT, id);
net.setNodeName(handle, name);
net.setNodePosition(handle, xPos, yPos, 85, 55);
int initialOutcomeCount = net.getOutcomeCount(handle);
for (int i = 0; i < initialOutcomeCount; i ++) {
net.setOutcomeId(handle, i, outcomes[i]);
}
for (int i = initialOutcomeCount; i < outcomes.length; i ++) {
net.addOutcome(handle, outcomes[i]);
}
return handle;
}
}