88 lines
2.6 KiB
C++
88 lines
2.6 KiB
C++
/* ----------------------------------------------------------------------------
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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 Assignment.h
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* @brief An assignment from labels to a discrete value index (size_t)
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* @author Frank Dellaert
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* @date Feb 5, 2012
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*/
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#pragma once
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#include <boost/foreach.hpp>
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#include <iostream>
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#include <vector>
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#include <map>
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namespace gtsam {
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/**
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* An assignment from labels to value index (size_t).
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* Assigns to each label a value. Implemented as a simple map.
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* A discrete factor takes an Assignment and returns a value.
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*/
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template<class L>
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class Assignment: public std::map<L, size_t> {
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public:
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void print(const std::string& s = "Assignment: ") const {
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std::cout << s << ": ";
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BOOST_FOREACH(const typename Assignment::value_type& keyValue, *this)
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std::cout << "(" << keyValue.first << ", " << keyValue.second << ")";
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std::cout << std::endl;
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}
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bool equals(const Assignment& other, double tol = 1e-9) const {
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return (*this == other);
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}
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}; //Assignment
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/**
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* @brief Get Cartesian product consisting all possible configurations
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* @param vector list of keys (label,cardinality) pairs.
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* @return vector list of all possible value assignments
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*
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* This function returns a vector of Assignment values for all possible
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* (Cartesian product) configurations of set of Keys which are nothing
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* but (Label,cardinality) pairs. This function should NOT be called for
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* more than a small number of variables and cardinalities. E.g. For 6
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* variables with each having cardinalities 4, we get 4096 possible
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* configurations!!
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*/
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template<typename L>
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std::vector<Assignment<L> > cartesianProduct(
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const std::vector<std::pair<L, size_t> >& keys) {
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std::vector<Assignment<L> > allPossValues;
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Assignment<L> values;
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typedef std::pair<L, size_t> DiscreteKey;
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BOOST_FOREACH(const DiscreteKey& key, keys)
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values[key.first] = 0; //Initialize from 0
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while (1) {
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allPossValues.push_back(values);
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size_t j = 0;
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for (j = 0; j < keys.size(); j++) {
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L idx = keys[j].first;
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values[idx]++;
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if (values[idx] < keys[j].second)
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break;
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//Wrap condition
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values[idx] = 0;
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}
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if (j == keys.size())
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break;
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}
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return allPossValues;
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}
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} // namespace gtsam
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