rmontanana/BayesNet
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Refactor Cestnik smoothin factor assuming m=1

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This commit is contained in:
Ricardo Montañana Gómez 2024-06-13 09:11:47 +02:00
parent b34869cc61
commit ca0ae4dacf
Signed by: rmontanana
GPG Key ID: 46064262FD9A7ADE
3 changed files with 70 additions and 5 deletions
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2
README.md
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@ -7,7 +7,7 @@
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Bayesian Network Classifiers using libtorch from scratch

4
bayesnet/network/Network.cc
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@ -204,8 +204,8 @@ namespace bayesnet {
case Smoothing_t::LAPLACE:
smoothing_factor = 1.0;
break;
case Smoothing_t::CESTNIK:
smoothing_factor = n_samples / numStates;
case Smoothing_t::CESTNIK: // Considering m=1 pa = 1/numStates
smoothing_factor = 1 / numStates;
break;
default:
throw std::invalid_argument("Smoothing method not recognized " + std::to_string(static_cast<int>(smoothing)));

69
tests/TestBayesNetwork.cc
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@ -15,6 +15,7 @@
#include "bayesnet/network/Node.h"
#include "bayesnet/utils/bayesnetUtils.h"
const double threshold = 1e-4;
void buildModel(bayesnet::Network& net, const std::vector<std::string>& features, const std::string& className)
{
std::vector<pair<int, int>> network = { {0, 1}, {0, 2}, {1, 3} };
@ -29,13 +30,11 @@ void buildModel(bayesnet::Network& net, const std::vector<std::string>& features
net.addEdge(className, feature);
}
}
TEST_CASE("Test Bayesian Network", "[Network]")
{
auto raw = RawDatasets("iris", true);
auto net = bayesnet::Network();
double threshold = 1e-4;
SECTION("Test get features")
{
@ -459,3 +458,69 @@ TEST_CASE("Dump CPT", "[Network]")
REQUIRE(res == expected);
}
TEST_CASE("Test Smoothing", "[Network]")
{
/*
Tomando m = 1 Pa = 0.5
Si estoy calculando P(A | C), con C en{ 0,1,2 } y tengo :
AC = { 11, 12, 11, 10, 10, 12, 10, 01, 00, 02 }
Entonces:
P(A = 1 | C = 0) = (3 + 1 / 2 * 1) / (4 + 1) = 3.5 / 5
P(A = 0 | C = 0) = (1 + 1 / 2 * 1) / (4 + 1) = 1.5 / 5
Donde m aquí es el número de veces de C = 0 que es la que condiciona y la a priori vuelve a ser sobre A que es sobre las que estaríamos calculando esas marginales.
P(A = 1 | C = 1) = (2 + 1 / 2 * 1) / (3 + 1) = 2.5 / 4
P(A = 0 | C = 1) = (1 + 1 / 2 * 1) / (3 + 1) = 1.5 / 4
P(A = 1 | C = 2) = (2 + 1 / 2 * 1) / (3 + 1) = 2.5 / 5
P(A = 0 | C = 2) = (1 + 1 / 2 * 1) / (3 + 1) = 1.5 / 5
En realidad es parecido a Laplace, que en este caso p.e.con C = 0 sería
P(A = 1 | C = 0) = (3 + 1) / (4 + 2) = 4 / 6
P(A = 0 | C = 0) = (1 + 1) / (4 + 2) = 2 / 6
*/
auto net = bayesnet::Network();
net.addNode("A");
net.addNode("C");
net.addEdge("C", "A");
std::vector<int> C = { 1, 2, 1, 0, 0, 2, 0, 1, 0, 2 };
std::vector<std::vector<int>> A = { { 1, 1, 1, 1, 1, 1, 1, 0, 0, 0 } };
std::map<std::string, std::vector<int>> states = { { "A", {0, 1} }, { "C", {0, 1, 2} } };
auto weights = std::vector<double>(C.size(), 1);
//
// Laplace
//
net.fit(A, C, weights, { "A" }, "C", states, bayesnet::Smoothing_t::LAPLACE);
auto cpt_c_laplace = net.getNodes().at("C")->getCPT();
REQUIRE(cpt_c_laplace.size(0) == 3);
auto laplace_c = std::vector<float>({ 0.3846, 0.3077, 0.3077 });
for (int i = 0; i < laplace_c.size(); ++i) {
REQUIRE(cpt_c_laplace.index({ i }).item<float>() == Catch::Approx(laplace_c[i]).margin(threshold));
}
auto cpt_a_laplace = net.getNodes().at("A")->getCPT();
REQUIRE(cpt_a_laplace.size(0) == 2);
REQUIRE(cpt_a_laplace.size(1) == 3);
auto laplace_a = std::vector<std::vector<float>>({ {0.3333, 0.4000,0.4000}, {0.6667, 0.6000, 0.6000} });
for (int i = 0; i < 2; ++i) {
for (int j = 0; j < 3; ++j) {
REQUIRE(cpt_a_laplace.index({ i, j }).item<float>() == Catch::Approx(laplace_a[i][j]).margin(threshold));
}
}
//
// Cestnik
//
net.fit(A, C, weights, { "A" }, "C", states, bayesnet::Smoothing_t::CESTNIK);
auto cpt_c_cestnik = net.getNodes().at("C")->getCPT();
REQUIRE(cpt_c_cestnik.size(0) == 3);
auto cestnik_c = std::vector<float>({ 0.3939, 0.3030, 0.3030 });
for (int i = 0; i < laplace_c.size(); ++i) {
REQUIRE(cpt_c_cestnik.index({ i }).item<float>() == Catch::Approx(cestnik_c[i]).margin(threshold));
}
auto cpt_a_cestnik = net.getNodes().at("A")->getCPT();
REQUIRE(cpt_a_cestnik.size(0) == 2);
REQUIRE(cpt_a_cestnik.size(1) == 3);
auto cestnik_a = std::vector<std::vector<float>>({ {0.3000, 0.3750, 0.3750}, {0.7000, 0.6250, 0.6250} });
for (int i = 0; i < 2; ++i) {
for (int j = 0; j < 3; ++j) {
REQUIRE(cpt_a_cestnik.index({ i, j }).item<float>() == Catch::Approx(cestnik_a[i][j]).margin(threshold));
}
}
}