143 lines
3.6 KiB
C++
143 lines
3.6 KiB
C++
/**
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* @file LinearConstraint.h
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* @brief Class that implements linear equality constraints
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* @author Alex Cunningham
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*/
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#ifndef EQUALITYFACTOR_H_
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#define EQUALITYFACTOR_H_
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#include <list>
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#include <set>
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#include "Matrix.h"
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#include "ConstrainedConditionalGaussian.h"
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namespace gtsam {
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/**
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* Linear constraints are similar to factors in structure, but represent
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* a different problem
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*/
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class LinearConstraint: Testable<LinearConstraint> {
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public:
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typedef boost::shared_ptr<LinearConstraint> 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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public:
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/**
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* Default constructor
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*/
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LinearConstraint();
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/**
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* Constructor with initialization of a unary equality factor
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* Creates an identity matrix for the underlying implementation and the constraint
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* value becomes the RHS value - use for setting a variable to a fixed value
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* @param constraint the value that the variable node is defined as equal to
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* @param key identifier for the variable node
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*/
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LinearConstraint(const Vector& constraint, const std::string& key);
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/**
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* Constructor for binary constraint
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* @param key for first node
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* @param A Matrix for first node
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* @param key for second node
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* @param A Matrix for second node
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* @param RHS b vector
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*/
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LinearConstraint(const std::string& node1, const Matrix& A1,
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const std::string& node2, const Matrix& A2, const Vector& b);
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/**
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* Constructor for arbitrary numbers of nodes
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* @param matrices is the full map of A matrices
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* @param b is the RHS vector
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*/
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LinearConstraint(const std::map<std::string, Matrix>& matrices,
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const Vector& b);
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/**
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* Default Destructor
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*/
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~LinearConstraint() {
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}
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/**
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* print
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* @param s optional string naming the factor
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*/
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void print(const std::string& s = "") const;
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/**
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* equality up to tolerance
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*/
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bool equals(const LinearConstraint& f, double tol = 1e-9) const;
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/**
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* Eliminates the constraint
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* Note: Assumes that the constraint will be completely eliminated
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* and that the matrix associated with the key is invertible
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* @param key is the variable to eliminate
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* @return a constrained conditional gaussian for the variable that is a
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* function of its parents
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*/
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ConstrainedConditionalGaussian::shared_ptr
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eliminate(const std::string& key);
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/**
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* returns a version of the factor as a string
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*/
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std::string dump() const;
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/** get a copy of b */
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const Vector& get_b() const {
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return b;
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}
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/** check if the constraint is connected to a particular node */
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bool involves(const std::string& key) const;
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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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/**
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* Gets all of the keys connected in a constraint
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* @param key is a key to leave out of the final set
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* @return a list of the keys for nodes connected to the constraint
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*/
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std::list<std::string> keys(const std::string& key = "") const;
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/**
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* @return the number of nodes the constraint connects
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*/
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std::size_t size() const {
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return As.size();
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}
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// friends
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friend LinearConstraint::shared_ptr combineConstraints(const std::set<LinearConstraint::shared_ptr>& constraints);
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};
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/**
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* Combines constraints into one constraint
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*/
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LinearConstraint::shared_ptr combineConstraints(const std::set<LinearConstraint::shared_ptr>& constraints);
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}
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#endif /* EQUALITYFACTOR_H_ */
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