/**
* Tests that models can be created that have multiple factors over the same variable, and that
* potentialOfVertex returns the product in that case.
*/
public void testMultipleNodePotentials() {
Variable var = new Variable(2);
FactorGraph mdl = new FactorGraph(new Variable[] {var});
Factor ptl1 = new TableFactor(var, new double[] {0.5, 0.5});
mdl.addFactor(ptl1);
Factor ptl2 = new TableFactor(var, new double[] {0.25, 0.25});
mdl.addFactor(ptl2);
// verify that factorOf(var) doesn't work
try {
mdl.factorOf(var);
fail();
} catch (RuntimeException e) {
} // expected
List factors = mdl.allFactorsOf(var);
Factor total = TableFactor.multiplyAll(factors);
double[] expected = {0.125, 0.125};
assertTrue(
"Arrays not equal\n Expected "
+ ArrayUtils.toString(expected)
+ "\n Actual "
+ ArrayUtils.toString(((TableFactor) total).toValueArray()),
Arrays.equals(expected, ((TableFactor) total).toValueArray()));
}
/**
* Tests that models can be created that have multiple factors over the same edge, and that
* potentialOfEdge returns the product in that case.
*/
public void testMultipleEdgePotentials() {
Variable v1 = new Variable(2);
Variable v2 = new Variable(2);
Variable[] vars = new Variable[] {v1, v2};
FactorGraph mdl = new FactorGraph(vars);
Factor ptl1 = new TableFactor(vars, new double[] {0.5, 0.5, 0.5, 0.5});
mdl.addFactor(ptl1);
Factor ptl2 = new TableFactor(vars, new double[] {0.25, 0.25, 0.5, 0.5});
mdl.addFactor(ptl2);
try {
mdl.factorOf(v1, v2);
fail();
} catch (RuntimeException e) {
}
Collection factors = mdl.allFactorsContaining(new HashVarSet(vars));
assertEquals(2, factors.size());
assertTrue(factors.contains(ptl1));
assertTrue(factors.contains(ptl2));
double[] vals = {0.125, 0.125, 0.25, 0.25};
Factor total = TableFactor.multiplyAll(factors);
Factor expected = new TableFactor(vars, vals);
assertTrue(
"Arrays not equal\n Expected "
+ ArrayUtils.toString(vals)
+ "\n Actual "
+ ArrayUtils.toString(((TableFactor) total).toValueArray()),
expected.almostEquals(total, 1e-10));
}
private void verifyCachesConsistent(FactorGraph mdl) {
Factor pot, pot2, pot3;
for (Iterator it = mdl.factors().iterator(); it.hasNext(); ) {
pot = (Factor) it.next();
// System.out.println("Testing model "+i+" potential "+pot);
Object[] vars = pot.varSet().toArray();
switch (vars.length) {
case 1:
pot2 = mdl.factorOf((Variable) vars[0]);
assertTrue(pot == pot2);
break;
case 2:
Variable var1 = (Variable) vars[0];
Variable var2 = (Variable) vars[1];
pot2 = mdl.factorOf(var1, var2);
pot3 = mdl.factorOf(var2, var1);
assertTrue(pot == pot2);
assertTrue(pot2 == pot3);
break;
// Factors of size > 2 aren't now cached.
default:
break;
}
}
}
public void testOutputToDot() throws IOException {
FactorGraph mdl = TestInference.createRandomGrid(3, 4, 2, new Random(4234));
PrintWriter out = new PrintWriter(new FileWriter(new File("grmm-model.dot")));
mdl.printAsDot(out);
out.close();
System.out.println("Now you can open up grmm-model.dot in Graphviz.");
}
private Assignment initialAssignment(FactorGraph mdl) {
Assignment assn = new Assignment(mdl, new int[mdl.numVariables()]);
if (mdl.logValue(assn) > Double.NEGATIVE_INFINITY) return assn;
assn = new Assignment();
return initialAssignmentRec(mdl, assn, 0);
}
// backtracking search for a feasible assignment
private Assignment initialAssignmentRec(FactorGraph mdl, Assignment assn, int fi) {
if (fi >= mdl.factors().size()) return assn;
Factor f = mdl.getFactor(fi);
Factor sliced = f.slice(assn);
if (sliced.varSet().isEmpty()) {
double val = f.value(assn);
if (val > 1e-50) {
return initialAssignmentRec(mdl, assn, fi + 1);
} else {
return null;
}
}
for (AssignmentIterator it = sliced.assignmentIterator(); it.hasNext(); ) {
double val = sliced.value(it);
if (val > 1e-50) {
Assignment new_assn = Assignment.union(assn, it.assignment());
Assignment assn_ret = initialAssignmentRec(mdl, new_assn, fi + 1);
if (assn_ret != null) return assn_ret;
}
it.advance();
}
return null;
}
public void testPotentialConnections() {
Variable v1 = new Variable(2);
Variable v2 = new Variable(2);
Variable v3 = new Variable(2);
Variable[] vars = new Variable[] {v1, v2, v3};
FactorGraph mdl = new FactorGraph();
TableFactor ptl = new TableFactor(vars, new double[8]);
mdl.addFactor(ptl);
assertTrue(mdl.isAdjacent(v1, v2));
assertTrue(mdl.isAdjacent(v2, v3));
assertTrue(mdl.isAdjacent(v1, v3));
}
public void testFactorOfSet() {
Variable[] vars = new Variable[3];
for (int i = 0; i < vars.length; i++) {
vars[i] = new Variable(2);
}
Factor factor = new TableFactor(vars, new double[] {0, 1, 2, 3, 4, 5, 6, 7});
FactorGraph fg = new FactorGraph(vars);
fg.addFactor(factor);
assertTrue(factor == fg.factorOf(factor.varSet()));
HashSet set = new HashSet(factor.varSet());
assertTrue(factor == fg.factorOf(set));
set.remove(vars[0]);
assertTrue(null == fg.factorOf(set));
}
private Assignment doOnePass(FactorGraph mdl, Assignment initial) {
Assignment ret = (Assignment) initial.duplicate();
for (int vidx = 0; vidx < ret.size(); vidx++) {
Variable var = mdl.get(vidx);
DiscreteFactor subcpt = constructConditionalCpt(mdl, var, ret);
int value = subcpt.sampleLocation(r);
ret.setValue(var, value);
}
return ret;
}
/**
* Constructs a junction tree from a given factor graph. Does not perform BP in the resulting
* graph. So this gives you the structure of a jnuction tree, but the factors don't correspond to
* the true marginals unless you call BP yourself.
*
* @param mdl Factor graph to compute JT for.
*/
public JunctionTree buildJunctionTree(FactorGraph mdl) {
jtCurrent = (JunctionTree) mdl.getInferenceCache(JunctionTreeInferencer.class);
if (jtCurrent != null) {
jtCurrent.clearCPFs();
} else {
/* The graph g is the topology of the MRF that corresponds to the factor graph mdl.
* Essentially, this means that we triangulate factor graphs by converting to an MRF first.
* I could have chosen to trianglualte the FactorGraph directly, but I didn't for historical reasons
* (I already had a version of triangulate() for MRFs, not bipartite factor graphs.)
* Note that the call to mdlToGraph() is perfectly valid for FactorGraphs that are also DirectedModels,
* and has the effect of moralizing in that case. */
UndirectedGraph g = Graphs.mdlToGraph(mdl);
triangulate(g);
jtCurrent = buildJtStructure();
mdl.setInferenceCache(JunctionTreeInferencer.class, jtCurrent);
}
initJtCpts(mdl, jtCurrent);
return jtCurrent;
}
public void testThreeNodeModel() {
Random r = new Random(23534709);
FactorGraph mdl = new FactorGraph();
Variable root = new Variable(2);
Variable childL = new Variable(2);
Variable childR = new Variable(2);
mdl.addFactor(root, childL, RandomGraphs.generateMixedPotentialValues(r, 1.5));
mdl.addFactor(root, childR, RandomGraphs.generateMixedPotentialValues(r, 1.5));
// assertTrue (mdl.isConnected (root, childL));
// assertTrue (mdl.isConnected (root, childR));
// assertTrue (mdl.isConnected (childL, childR));
assertTrue(mdl.isAdjacent(root, childR));
assertTrue(mdl.isAdjacent(root, childL));
assertTrue(!mdl.isAdjacent(childL, childR));
assertTrue(mdl.factorOf(root, childL) != null);
assertTrue(mdl.factorOf(root, childR) != null);
}
// Warning: destructively modifies ret's assignment to fullAssn (I could save and restore, but I
// don't care
private DiscreteFactor constructConditionalCpt(
FactorGraph mdl, Variable var, Assignment fullAssn) {
List ptlList = mdl.allFactorsContaining(var);
LogTableFactor ptl = new LogTableFactor(var);
for (AssignmentIterator it = ptl.assignmentIterator(); it.hasNext(); it.advance()) {
Assignment varAssn = it.assignment();
fullAssn.setValue(var, varAssn.get(var));
ptl.setRawValue(varAssn, sumValues(ptlList, fullAssn));
}
ptl.normalize();
return ptl;
}
// Verify that potentialOfVertex and potentialOfEdge (which use
// caches) are consistent with the potentials set even if a vertex is removed.
public void testUndirectedCachesAfterRemove() {
List models = TestInference.createTestModels();
for (Iterator mdlIt = models.iterator(); mdlIt.hasNext(); ) {
FactorGraph mdl = (FactorGraph) mdlIt.next();
mdl = (FactorGraph) mdl.duplicate();
mdl.remove(mdl.get(0));
// Verify that indexing correct
for (Iterator it = mdl.variablesIterator(); it.hasNext(); ) {
Variable var = (Variable) it.next();
int idx = mdl.getIndex(var);
assertTrue(idx >= 0);
assertTrue(idx < mdl.numVariables());
}
// Verify that caches consistent
verifyCachesConsistent(mdl);
}
}
private void initJtCpts(FactorGraph mdl, JunctionTree jt) {
for (Iterator it = jt.getVerticesIterator(); it.hasNext(); ) {
VarSet c = (VarSet) it.next();
// DiscreteFactor ptl = createBlankFactor (c);
// jt.setCPF(c, ptl);
jt.setCPF(c, new ConstantFactor(1.0));
}
for (Iterator it = mdl.factors().iterator(); it.hasNext(); ) {
Factor ptl = (Factor) it.next();
VarSet parent = jt.findParentCluster(ptl.varSet());
assert parent != null : "Unable to find parent cluster for ptl " + ptl + "in jt " + jt;
Factor cpf = jt.getCPF(parent);
Factor newCpf = cpf.multiply(ptl);
jt.setCPF(parent, newCpf);
/* debug
if (jt.isNaN()) {
throw new RuntimeException ("Got a NaN");
}
*/
}
}
public void computeMarginals(FactorGraph mdl) {
inLogSpace = mdl.getFactor(0) instanceof LogTableFactor;
buildJunctionTree(mdl);
propagator.computeMarginals(jtCurrent);
totalMessagesSent += propagator.getTotalMessagesSent();
}