248 lines
6.9 KiB
C++
248 lines
6.9 KiB
C++
/**
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* @file LinearFactor.h
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* @brief Linear Factor....A Gaussian
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* @brief linearFactor
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* @author Christian Potthast
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*/
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// \callgraph
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#pragma once
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#include <boost/shared_ptr.hpp>
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#include <boost/serialization/map.hpp>
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#include "Factor.h"
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#include "Matrix.h"
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#include "VectorConfig.h"
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namespace gtsam {
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class ConditionalGaussian;
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class Ordering;
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/**
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* Base Class for a linear factor.
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* LinearFactor is non-mutable (all methods const!).
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* The factor value is exp(-0.5*||Ax-b||^2)
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*/
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class LinearFactor: public Factor<VectorConfig> {
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public:
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typedef boost::shared_ptr<LinearFactor> shared_ptr;
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typedef std::map<std::string, Matrix>::iterator iterator;
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typedef std::map<std::string, Matrix>::const_iterator const_iterator;
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protected:
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std::map<std::string, Matrix> As_; // linear matrices
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Vector b_; // right-hand-side
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Vector sigmas_; // vector of standard deviations for each row in the factor
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public:
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// TODO: eradicate, as implies non-const
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LinearFactor() {
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}
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/** Construct Null factor */
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LinearFactor(const Vector& b_in) :
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b_(b_in), sigmas_(ones(b_in.size())){
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}
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/** Construct unary factor */
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LinearFactor(const std::string& key1, const Matrix& A1,
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const Vector& b_in, double sigma) :
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b_(b_in), sigmas_(repeat(b_in.size(),sigma)) {
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As_.insert(make_pair(key1, A1));
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}
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/** Construct binary factor */
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LinearFactor(const std::string& key1, const Matrix& A1,
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const std::string& key2, const Matrix& A2,
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const Vector& b_in, double sigma) :
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b_(b_in), sigmas_(repeat(b_in.size(),sigma)) {
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As_.insert(make_pair(key1, A1));
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As_.insert(make_pair(key2, A2));
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}
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/** Construct ternary factor */
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LinearFactor(const std::string& key1, const Matrix& A1,
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const std::string& key2, const Matrix& A2,
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const std::string& key3, const Matrix& A3,
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const Vector& b_in, double sigma) :
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b_(b_in), sigmas_(repeat(b_in.size(),sigma)) {
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As_.insert(make_pair(key1, A1));
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As_.insert(make_pair(key2, A2));
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As_.insert(make_pair(key3, A3));
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}
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/** Construct an n-ary factor */
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LinearFactor(const std::vector<std::pair<std::string, Matrix> > &terms,
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const Vector &b_in, double sigma) :
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b_(b_in), sigmas_(repeat(b_in.size(),sigma)) {
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for(unsigned int i=0; i<terms.size(); i++)
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As_.insert(terms[i]);
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}
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/** Construct an n-ary factor with a multiple sigmas*/
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LinearFactor(const std::vector<std::pair<std::string, Matrix> > &terms,
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const Vector &b_in, const Vector& sigmas) :
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b_(b_in), sigmas_(sigmas) {
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for (unsigned int i = 0; i < terms.size(); i++)
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As_.insert(terms[i]);
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}
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/** Construct from Conditional Gaussian */
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LinearFactor(const boost::shared_ptr<ConditionalGaussian>& cg);
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/**
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* Constructor that combines a set of factors
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* @param factors Set of factors to combine
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*/
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LinearFactor(const std::vector<shared_ptr> & factors);
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// Implementing Testable virtual functions
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void print(const std::string& s = "") const;
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bool equals(const Factor<VectorConfig>& lf, double tol = 1e-9) const;
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// Implementing Factor virtual functions
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double error(const VectorConfig& c) const; /** 0.5*(A*x-b)'*D*(A*x-b) */
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std::size_t size() const { return As_.size();}
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/** STL like, return the iterator pointing to the first node */
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const_iterator const begin() const { return As_.begin();}
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/** STL like, return the iterator pointing to the last node */
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const_iterator const end() const { return As_.end(); }
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/** check if empty */
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bool empty() const { return b_.size() == 0;}
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/** get a copy of b */
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const Vector& get_b() const { return b_; }
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/** get a copy of precisions */
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const Vector& get_precisions() const { return sigmas_; }
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/**
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* get a copy of the A matrix from a specific node
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* O(log n)
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*/
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const Matrix& get_A(const std::string& key) const {
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const_iterator it = As_.find(key);
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if (it == As_.end())
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throw(std::invalid_argument("LinearFactor::[] invalid key: " + key));
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return it->second;
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}
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/** operator[] syntax for get */
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inline const Matrix& operator[](const std::string& name) const {
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return get_A(name);
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}
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/** Check if factor involves variable with key */
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bool involves(const std::string& key) const {
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const_iterator it = As_.find(key);
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return (it != As_.end());
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}
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/**
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* return the number of rows from the b vector
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* @return a integer with the number of rows from the b vector
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*/
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int numberOfRows() const { return b_.size();}
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/**
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* Find all variables
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* @return The set of all variable keys
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*/
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std::list<std::string> keys() const;
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/**
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* Find all variables and their dimensions
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* @return The set of all variable/dimension pairs
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*/
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VariableSet variables() const;
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/**
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* Get the dimension of a particular variable
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* @param key is the name of the variable
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* @return the size of the variable
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*/
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size_t getDim(const std::string& key) const;
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/**
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* Add to separator set if this factor involves key, but don't add key itself
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* @param key
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* @param separator set to add to
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*/
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void tally_separator(const std::string& key,
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std::set<std::string>& separator) const;
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/**
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* Return (dense) matrix associated with factor
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* NOTE: in this case, the precisions are baked into A and b
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* @param ordering of variables needed for matrix column order
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*/
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std::pair<Matrix, Vector> matrix(const Ordering& ordering) const;
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/**
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* Return (dense) matrix associated with factor
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* The returned system is an augmented matrix: [A b]
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* @param ordering of variables needed for matrix column order
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*/
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Matrix matrix_augmented(const Ordering& ordering) const;
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/* ************************************************************************* */
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// MUTABLE functions. FD:on the path to being eradicated
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/* ************************************************************************* */
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/** insert, copies A */
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void insert(const std::string& key, const Matrix& A) {
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As_.insert(std::make_pair(key, A));
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}
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/** set RHS, copies b */
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void set_b(const Vector& b) {
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this->b_ = b;
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}
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// set A matrices for the linear factor, same as insert ?
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inline void set_A(const std::string& key, const Matrix &A) {
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insert(key, A);
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}
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/**
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* Current Implementation: Full QR factorization
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* eliminate (in place!) one of the variables connected to this factor
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* @param key the key of the node to be eliminated
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* @return a new factor and a conditional gaussian on the eliminated variable
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*/
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std::pair<boost::shared_ptr<ConditionalGaussian>, shared_ptr> eliminate(const std::string& key);
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/**
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* Take the factor f, and append to current matrices. Not very general.
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* @param f linear factor graph
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* @param m final number of rows of f, needs to be known in advance
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* @param pos where to insert in the m-sized matrices
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*/
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void append_factor(LinearFactor::shared_ptr f, const size_t m,
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const size_t pos);
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}; // LinearFactor
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/* ************************************************************************* */
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/**
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* creates a C++ string a la "x3", "m768"
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* @param c the base character
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* @param index the integer to be added
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* @return a C++ string
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*/
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std::string symbol(char c, int index);
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} // namespace gtsam
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