LocalSolver Class¶

Summary¶

Instance methods¶

LocalSolver.get_state()¶

Gets the state of this LocalSolver environment. This method can be called in any state. In particular, this method can be called in state LSState.RUNNING.

You can also use the shortcut member state

Returns:	State of LocalSolver.
Return type:	LSState

LocalSolver.get_model()¶

Gets the model associated to this LocalSolver environment. Once the model is created and closed, the solver can be launched with solve().

You can also use the shortcut member model

Returns:	Model
Return type:	LSModel

LocalSolver.get_param()¶

Gets the parameters of this LocalSolver environment.

You can also use the shortcut member param

Returns:	Parameters
Return type:	LSParam

LocalSolver.solve()¶

Solves the model. This method returns only when the time limit, the iteration limit or the objective bounds are reached. The model must be closed to launch the resolution.

LocalSolver.compute_inconsistency()¶

Computes an inconsistency core for this model. Only allowed in state LSState.STOPPED.

LocalSolver.stop()¶

Aborts the resolution previously launched using solve(). If no resolution was launched, this method does nothing. Called from another thread, this method enables users to stop the resolution properly. Solution and statistics remain valid. This method can be called in any state, notably in state LSState.RUNNING.

LocalSolver.create_phase()¶

Adds a new phase to this LocalSolver environment. Only allowed in state LSState.STOPPED.

Returns:	Created phase.
Return type:	LSPhase

LocalSolver.get_phase(phase_id)¶

Gets the phase with the given index. Only allowed in states LSState.PAUSED or LSState.STOPPED.

You can also use the shortcut collection phases.

Parameters:	phase_id (int) – Index of the phase
Returns:	Phase
Return type:	LSPhase

LocalSolver.get_nb_phases()¶

Gets the number of phases. Only allowed in states LSState.PAUSED or LSState.STOPPED.

You can also use the shortcut collection phases.

Returns:	Number of phases.
Return type:	int

LocalSolver.get_solution()¶

Gets the best solution found by the solver. If the solver has not been started at least once, all the decision variables of the solution are set to 0 (such a solution may be infeasible). Only allowed in states LSState.PAUSED or LSState.STOPPED.

You can also use the shortcut member solution

Returns:	The best solution.
Return type:	LSSolution

LocalSolver.get_statistics()¶

Gets the statistics of this LocalSolver environment. Statistics are reset to zero before each resolution. Only allowed in states LSState.PAUSED or LSState.STOPPED. Note that for performance reasons, this function always returns the same object.

You can also use the shortcut member statistics

Returns:	Statistics.
Return type:	LSStatistics

LocalSolver.get_info()¶

Returns useful info about the search while running. Only allowed if the solver has been started at least once. Only allowed in states LSState.PAUSED or LSState.STOPPED. Useful for debugging or logging purposes. Here are some explanations about the output string:

• “sec” stands for the number of seconds.
• “itr” stands for the number of iterations.
• “infeas” corresponds to the infeasibility score of the best solution found, if infeasible.
• “obj” corresponds to the objective values of the best solution found, if feasible.
• “mov” corresponds to the number of moves performed.
• “inf” corresponds to the percentage of infeasible moves.
• “acc” corresponds to the percentage of accepted moves.
• “imp” corresponds to the number of improving moves.

You can also use the shortcut member info

Returns:	Info about the search while running
Return type:	str

LocalSolver.save_environment(filename)¶

Exports the complete environment (model, parameters, solution, ..) in a file. This method is useful to debug or replay a model in the same conditions.

Currently, this function supports 2 file formats : LSM and LSB. These two formats reproduce all the parameters and the features of this API. The main difference between LSM and LSB files is the way the fields are organized : LSB files are binary files. They are less readable but offer better performance and are more space-efficient than LSM files.

The chosen file format is determined by the file suffix. An exception is thrown if the provided file suffix is not supported. The suffix may optionally be followed by .gz. In that case, this function produces a compressed result (using deflate algorithm).

Parameters:	filename (str) – Name of the file.
Since:	3.0

LocalSolver.load_environment(filename)¶

Import a complete environment or a model from a file. Only allowed in state LSState.MODELING. The current model must be empty.

Currently, this function supports 4 main file formats : LSM, LSB, LP and MPS. The first two are preferable since they are the native format of LocalSolver. The other ones are classically used by linear programming solvers. LocalSolver supports only a subset of features exposed by these last formats. Please refer to the documentation for more details on this subject.

The chosen file format is determined by the file suffix. An exception is thrown if the provided file suffix is not supported. The suffix may optionally be followed by .gz. In that case, this function uncompress the stream before reading.

Parameters:	filename (str) – Name of the file.
Since:	3.0

LocalSolver.add_callback(type, callback)¶

Add a new callback for a specific event type. The callback will be called each time the given event occurs. When a callback is called, the solver is paused. You can stop the resolution from a callback, retrieve the current solution, retrieve the statistics of the solver and, in general, call all the methods marked as “allowed in state LSState.PAUSED”.

The same callback can be used for different events. Only allowed in states LSState.STOPPED or LSState.MODELING.

The callback function must accept 2 parameters that are respectively the LocalSolver environment and the type of the event.

Parameters:	type (LSCallbackType) – Event to watch. callback (function) – User callback. Cannot be null.
Since:	4.0

LocalSolver.remove_callback(type, callback)¶

Remove the callback for the given event type.

Parameters:	type (LSCallbackType) – Event callback (function) – User callback to delete
Returns:	False if the callback was not added for the given event, True otherwise.
Return type:	bool
Since:	4.0

Instance attributes¶

All get/set methods have their attribute counterpart. You can use them as shortcuts to improve the readability or your models and codes.

LocalSolver.state¶

State of the solver. This attribute is read-only. It is a shortcut for get_state().

LocalSolver.model¶

Model associated to this environment. This attribute is read-only. It is a shortcut for get_model().

LocalSolver.param¶

Parameters of the model. This attribute is read-only. It is a shortcut for get_param().

LocalSolver.phases¶

List of the phases of the model. This attribute is read-only. The returned object is iterable, supports the len function and can be indexed with integers. It is a shortcut for get_phase() and get_nb_phases() methods. Please note, that you still have to use create_phase() to add phases.

LocalSolver.solution¶

Best solution found. This attribute is read-only. It is a shortcut for get_solution().

LocalSolver.statistics¶

Statistics. This attribute is read-only. It is a shortcut for get_statistics().

LocalSolver.info¶

Useful info about the search. This attribute is read-only. It is a shortcut for get_info().

Special operators and methods¶

LocalSolver.__str__()¶

Returns a string representation of this LocalSolver environment. This representation provides useful info related to the model, the parameters, and the phases (if any). Useful for debugging or logging purposes.

Returns:	String representation of this LocalSolver.
Return type:	str