--— 2Opt --— More...

Inheritance diagram for operations_research::TwoOpt:

Public Member Functions
	TwoOpt (const std::vector< IntVar * > &vars, const std::vector< IntVar * > &secondary_vars, std::function< int(int64_t)> start_empty_path_class, std::function< const std::vector< int > &(int, int)> get_neighbors=nullptr)

	~TwoOpt () override

bool	MakeNeighbor () override

bool	IsIncremental () const override

void	Reset () override

std::string	DebugString () const override

Public Member Functions inherited from operations_research::PathOperator
	PathOperator (const std::vector< IntVar * > &next_vars, const std::vector< IntVar * > &path_vars, IterationParameters iteration_parameters)
	Builds an instance of PathOperator from next and path variables.

	PathOperator (const std::vector< IntVar * > &next_vars, const std::vector< IntVar * > &path_vars, int number_of_base_nodes, bool skip_locally_optimal_paths, bool accept_path_end_base, std::function< int(int64_t)> start_empty_path_class, std::function< const std::vector< int > &(int, int)> get_neighbors)

	~PathOperator () override

bool	SkipUnchanged (int index) const override

int64_t	Next (int64_t node) const
	Returns the node after node in the current delta.

int64_t	Prev (int64_t node) const
	Returns the node before node in the current delta.

int64_t	Path (int64_t node) const

int	number_of_nexts () const
	Number of next variables.

Public Member Functions inherited from operations_research::IntVarLocalSearchOperator
	IntVarLocalSearchOperator (const std::vector< IntVar * > &vars, bool keep_inverse_values=false)

	~IntVarLocalSearchOperator () override

bool	HoldsDelta () const override

void	Start (const Assignment *assignment) override

int	Size () const

int64_t	Value (int64_t index) const

IntVar *	Var (int64_t index) const
	Returns the variable of given index.

int64_t	OldValue (int64_t index) const

int64_t	PrevValue (int64_t index) const

void	SetValue (int64_t index, int64_t value)

bool	Activated (int64_t index) const

void	Activate (int64_t index)

void	Deactivate (int64_t index)

bool	ApplyChanges (Assignment delta, Assignment deltadelta) const

void	RevertChanges (bool change_was_incremental)

void	AddVars (const std::vector< IntVar * > &vars)

bool	MakeNextNeighbor (Assignment delta, Assignment deltadelta) override
	--— Base operator class for operators manipulating IntVars --—

Public Member Functions inherited from operations_research::LocalSearchOperator
	LocalSearchOperator ()

	~LocalSearchOperator () override

virtual const LocalSearchOperator *	Self () const

virtual bool	HasFragments () const

Public Member Functions inherited from operations_research::BaseObject
	BaseObject ()

	BaseObject (const BaseObject &)=delete
	This type is neither copyable nor movable.

BaseObject &	operator= (const BaseObject &)=delete

virtual	~BaseObject ()

Protected Member Functions
bool	OnSamePathAsPreviousBase (int64_t) override

int64_t	GetBaseNodeRestartPosition (int base_index) override

Protected Member Functions inherited from operations_research::PathOperator
bool	MakeOneNeighbor () override
	This method should not be overridden. Override MakeNeighbor() instead.

int64_t	BaseNode (int i) const
	Returns the ith base node of the operator.

int	BaseAlternative (int i) const
	Returns the alternative for the ith base node.

int64_t	BaseAlternativeNode (int i) const
	Returns the alternative node for the ith base node.

int	BaseSiblingAlternative (int i) const
	Returns the alternative for the sibling of the ith base node.

int64_t	BaseSiblingAlternativeNode (int i) const
	Returns the alternative node for the sibling of the ith base node.

int64_t	StartNode (int i) const
	Returns the start node of the ith base node.

int64_t	EndNode (int i) const
	Returns the end node of the ith base node.

const std::vector< int64_t > &	path_starts () const
	Returns the vector of path start nodes.

int	PathClass (int i) const
	Returns the class of the path of the ith base node.

int	PathClassFromStartNode (int64_t start_node) const

virtual bool	RestartAtPathStartOnSynchronize ()

virtual void	SetNextBaseToIncrement (int64_t base_index)

virtual bool	ConsiderAlternatives (int64_t base_index) const

int64_t	OldNext (int64_t node) const

int64_t	PrevNext (int64_t node) const

int64_t	OldPrev (int64_t node) const

int64_t	OldPath (int64_t node) const

int	CurrentNodePathStart (int64_t node) const

int	CurrentNodePathEnd (int64_t node) const

bool	MoveChain (int64_t before_chain, int64_t chain_end, int64_t destination)

bool	ReverseChain (int64_t before_chain, int64_t after_chain, int64_t *chain_last)

bool	MakeActive (int64_t node, int64_t destination)
	Insert the inactive node after destination.

bool	MakeChainInactive (int64_t before_chain, int64_t chain_end)

bool	SwapActiveAndInactive (int64_t active, int64_t inactive)
	Replaces active by inactive in the current path, making active inactive.

void	SetNext (int64_t from, int64_t to, int64_t path)
	Sets 'to' to be the node after 'from' on the given path.

bool	IsPathEnd (int64_t node) const

bool	IsPathStart (int64_t node) const
	Returns true if node is the first node on the path.

bool	IsInactive (int64_t node) const
	Returns true if node is inactive.

virtual bool	InitPosition () const

void	ResetPosition ()

int	AddAlternativeSet (const std::vector< int64_t > &alternative_set)

template<typename PairType >
void	AddPairAlternativeSets (const std::vector< PairType > &pair_alternative_sets)

int64_t	GetActiveInAlternativeSet (int alternative_index) const
	Returns the active node in the given alternative set.

int64_t	GetActiveAlternativeNode (int node) const
	Returns the active node in the alternative set of the given node.

int	GetSiblingAlternativeIndex (int node) const
	Returns the index of the alternative set of the sibling of node.

int64_t	GetActiveAlternativeSibling (int node) const

bool	CheckChainValidity (int64_t before_chain, int64_t chain_end, int64_t exclude) const

bool	HasNeighbors () const

int	GetNeighborForBaseNode (int64_t base_index) const

Protected Member Functions inherited from operations_research::IntVarLocalSearchOperator
int64_t	InverseValue (int64_t index) const

int64_t	OldInverseValue (int64_t index) const

void	AddToAssignment (IntVar var, int64_t value, bool active, std::vector< int > assignment_indices, int64_t index, Assignment *assignment) const

Additional Inherited Members
Protected Attributes inherited from operations_research::PathOperator
const int	number_of_nexts_

const bool	ignore_path_vars_

Detailed Description

--— 2Opt --—

Reverses a sub-chain of a path. It is called 2Opt because it breaks 2 arcs on the path; resulting paths are called 2-optimal. Possible neighbors for the path 1 -> 2 -> 3 -> 4 -> 5 (where (1, 5) are first and last nodes of the path and can therefore not be moved): 1 -> 3 -> 2 -> 4 -> 5 1 -> 4 -> 3 -> 2 -> 5 1 -> 2 -> 4 -> 3 -> 5

Definition at line 897 of file local_search.cc.

Constructor & Destructor Documentation

◆ TwoOpt()

operations_research::TwoOpt::TwoOpt	(	const std::vector< IntVar * > &	vars,
		const std::vector< IntVar * > &	secondary_vars,
		std::function< int(int64_t)>	start_empty_path_class,
		std::function< const std::vector< int > &(int, int)>	get_neighbors = nullptr )

inline

Definition at line 899 of file local_search.cc.

◆ ~TwoOpt()

operations_research::TwoOpt::~TwoOpt ( )

inlineoverride

Definition at line 910 of file local_search.cc.

Member Function Documentation

◆ DebugString()

std::string operations_research::TwoOpt::DebugString ( ) const

inlineoverridevirtual

Reimplemented from operations_research::BaseObject.

Definition at line 922 of file local_search.cc.

◆ GetBaseNodeRestartPosition()

int64_t operations_research::TwoOpt::GetBaseNodeRestartPosition ( int base_index )

inlineoverrideprotectedvirtual

Returns the index of the node to which the base node of index base_index must be set to when it reaches the end of a path. By default, it is set to the start of the current path. When this method is called, one can only assume that base nodes with indices < base_index have their final position.

Reimplemented from operations_research::PathOperator.

Definition at line 929 of file local_search.cc.

◆ IsIncremental()

bool operations_research::TwoOpt::IsIncremental ( ) const

inlineoverridevirtual

Reimplemented from operations_research::IntVarLocalSearchOperator.

Definition at line 912 of file local_search.cc.

◆ MakeNeighbor()

bool operations_research::TwoOpt::MakeNeighbor ( )

overridevirtual

Incrementality is disabled with neighbors.

Check there are more than one node in the chain (reversing a single node is a NOP).

Implements operations_research::PathOperator.

Definition at line 940 of file local_search.cc.

◆ OnSamePathAsPreviousBase()

bool operations_research::TwoOpt::OnSamePathAsPreviousBase ( int64_t base_index )

inlineoverrideprotectedvirtual

Returns true if a base node has to be on the same path as the "previous" base node (base node of index base_index - 1). Useful to limit neighborhood exploration to nodes on the same path.

Todo: (user): ideally this should be OnSamePath(int64_t node1, int64_t node2); it's currently way more complicated to implement.

Both base nodes have to be on the same path.

Reimplemented from operations_research::PathOperator.

Definition at line 925 of file local_search.cc.

◆ Reset()

void operations_research::TwoOpt::Reset ( )

inlineoverridevirtual

When using metaheuristics, path operators will reactivate optimal routes and iterating will start at route starts, which can potentially be out of sync with the last incremental moves. This requires resetting incrementalism.

Reimplemented from operations_research::PathOperator.

Definition at line 913 of file local_search.cc.

The documentation for this class was generated from the following file:

ortools/constraint_solver/local_search.cc

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ TwoOpt()

◆ ~TwoOpt()

Member Function Documentation

◆ DebugString()

◆ GetBaseNodeRestartPosition()

◆ IsIncremental()

◆ MakeNeighbor()

◆ OnSamePathAsPreviousBase()

◆ Reset()