75 lines
2.1 KiB
C++
75 lines
2.1 KiB
C++
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/* ----------------------------------------------------------------------------
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* GTSAM Copyright 2010, Georgia Tech Research Corporation,
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* Atlanta, Georgia 30332-0415
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* All Rights Reserved
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* Authors: Frank Dellaert, et al. (see THANKS for the full author list)
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* See LICENSE for the license information
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* -------------------------------------------------------------------------- */
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/**
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* @file small.cpp
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* @brief UGM (undirected graphical model) examples: small
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* @author Frank Dellaert
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*
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* See http://www.di.ens.fr/~mschmidt/Software/UGM/small.html
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*/
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#include <gtsam/discrete/DiscreteFactorGraph.h>
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#include <gtsam/discrete/DiscreteSequentialSolver.h>
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using namespace std;
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using namespace gtsam;
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int main(int argc, char** argv) {
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// We will assume 2-state variables, where, to conform to the "small" example
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// we have 0 == "right answer" and 1 == "wrong answer"
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size_t nrStates = 2;
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// define variables
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DiscreteKey Cathy(1, nrStates), Heather(2, nrStates), Mark(3, nrStates),
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Allison(4, nrStates);
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// create graph
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DiscreteFactorGraph graph;
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// add node potentials
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graph.add(Cathy, "1 3");
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graph.add(Heather, "9 1");
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graph.add(Mark, "1 3");
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graph.add(Allison, "9 1");
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// add edge potentials
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graph.add(Cathy & Heather, "2 1 1 2");
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graph.add(Heather & Mark, "2 1 1 2");
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graph.add(Mark & Allison, "2 1 1 2");
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// Print the UGM distribution
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cout << "\nUGM distribution:" << endl;
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for (size_t a = 0; a < nrStates; a++)
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for (size_t m = 0; m < nrStates; m++)
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for (size_t h = 0; h < nrStates; h++)
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for (size_t c = 0; c < nrStates; c++) {
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DiscreteFactor::Values values;
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values[1] = c;
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values[2] = h;
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values[3] = m;
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values[4] = a;
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double prodPot = graph(values);
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cout << c << " " << h << " " << m << " " << a << " :\t"
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<< prodPot << "\t" << prodPot/3790 << endl;
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}
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// "Decoding", i.e., configuration with largest value
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// We use sequential variable elimination
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DiscreteSequentialSolver solver(graph);
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DiscreteFactor::sharedValues optimalDecoding = solver.optimize();
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optimalDecoding->print("\noptimalDecoding");
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return 0;
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}
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