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added probability function that computes the probability of a BinaryBayesNet given a config.

release/4.3a0
Manohar Paluri 2009-12-07 07:12:01 +00:00
parent 115d9a8adf
commit e244e22c6a
1 changed files with 17 additions and 5 deletions
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22
cpp/testBinaryBayesNet.cpp
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@ -31,6 +31,18 @@ using namespace gtsam;
/** A Bayes net made from binary conditional probability tables */
typedef BayesNet<BinaryConditional> BinaryBayesNet;
double probability( BinaryBayesNet & bbn, map<string,bool> & config)
{
double result = 1.0;
BinaryBayesNet::const_iterator it = bbn.begin();
while( it != bbn.end() ){
result *= (*it)->probability(config);
it++;
}
return result;
}
/************************************************************************** */
TEST( BinaryBayesNet, constructor )
{
@ -40,19 +52,19 @@ TEST( BinaryBayesNet, constructor )
// p(x|y=1) = 0.6
map<string,bool> config;
config["y"] = true;
config["x"] = true;
config["y"] = false;
config["x"] = false;
// unary conditional for y
boost::shared_ptr<BinaryConditional> py(new BinaryConditional("y",0.2));
py->print("py");
DOUBLES_EQUAL(0.2,py->probability(config),0.01);
DOUBLES_EQUAL(0.8,py->probability(config),0.01);
// single parent conditional for x
vector<double> cpt;
cpt += 0.3, 0.6 ; // array index corresponds to binary parent configuration
boost::shared_ptr<BinaryConditional> px_y(new BinaryConditional("x","y",cpt));
px_y->print("px_y");
DOUBLES_EQUAL(0.6,px_y->probability(config),0.01);
DOUBLES_EQUAL(0.7,px_y->probability(config),0.01);
// push back conditionals in topological sort order (parents last)
BinaryBayesNet bbn;
@ -60,7 +72,7 @@ TEST( BinaryBayesNet, constructor )
bbn.push_back(px_y);
// Test probability of 00,01,10,11
//DOUBLES_EQUAL(0.56,bbn.probability(config),0.01); // P(y=0)P(x=0|y=0) = 0.8 * 0.7 = 0.56;
DOUBLES_EQUAL(0.56,probability(bbn,config),0.01); // P(y=0)P(x=0|y=0) = 0.8 * 0.7 = 0.56;
}
/* ************************************************************************* */