LSPhase Class

class localsolver.LSPhase

Optimization phase. Since LocalSolver allows lexicographic multiobjective optimization, we allow you to parameterize the time or the number of iterations to spend in optimizing each objective. When multiple objectives are declared, these objectives are optimized in lexicographic order (in the order of their declaration in the model). Thus, if k objectives 0, ..., k-1 are declared, each objective i can be optimized while maintaining the values of objectives 0, ..., i-1 previously obtained and ignoring the values of objectives i+1, ..., k-1. During such an optimization phase, objective i is called the optimized objective.

Summary

Attributes

time_limit

Time limit of this phase in seconds.

iteration_limit

Iteration limit of this phase.

optimized_objective

Index of the optimized objective of this phase.

enabled

Enabled status of this phase.

Methods

set_time_limit

Sets the time limit of this phase in seconds.

get_time_limit

Gets the time limit of this phase in seconds.

set_iteration_limit

Sets the number of iterations of this phase.

get_iteration_limit

Gets the number of iterations of this phase.

set_optimized_objective

Sets the optimized objective of this phase.

get_optimized_objective

Gets the index of the optimized objective.

set_enabled

Sets the enabled status of this phase.

is_enabled

Returns true if the phase is enabled, False otherwise.

Special methods

__str__

Returns a string representation of this phase.

Instance methods

LSPhase.set_time_limit(limit)

Sets the time limit of this phase in seconds. Note that the “real” time (that is, total time) spent to resolve the model is considered here (and not only the CPU time). The default time limit is set to the largest positive integer on 32 bits, that is 2^31-1 = 2,147,483,647 > 10^9. Only allowed in states LSState.MODELING or LSState.STOPPED.

Note that if the optimal value of an objective is found before the end of the corresponding phase, the remaining time will be transferred to the next phase.

You can also use the shortcut member time_limit

Parameters

limit (int) – Time limit in seconds.

LSPhase.get_time_limit()

Gets the time limit of this phase in seconds.

You can also use the shortcut member time_limit

Returns

Time limit in seconds.

Return type

int

LSPhase.set_iteration_limit(limit)

Sets the number of iterations of this phase. Fixing the seed and the number of iterations of all phases ensures the reproducibility of results over several runs. The default number of iterations is set to the largest positive integer on 64 bits, that is 2^63-1 = 9,223,372,036,854,775,807 > 10^18. Only allowed in states LSState.MODELING or LSState.STOPPED.

Note that if the optimal value of an objective is found before the end of the corresponding phase, the remaining iterations will be transferred to the next phase.

You can also use the shortcut member iteration_limit

Parameters

limit (int) – Iteration limit

LSPhase.get_iteration_limit()

Gets the number of iterations of this phase. Only allowed in states LSState.PAUSED or LSState.STOPPED.

You can also use the shortcut member iteration_limit

Returns

Iteration limit

Return type

int

LSPhase.set_optimized_objective(obj_index)

Sets the optimized objective of this phase. When multiple objectives are declared, these objectives are optimized in lexicographic order (in the order of their declaration in the model). Thus, if k objectives 0, ..., k-1 are declared, each objective i can be optimized while maintaining the values of objectives 0, ..., i-1 previously obtained and ignoring the values of objectives i+1, ..., k-1. By default, the optimized objective corresponds to the last objective declared in the model. Only allowed in states LSState.MODELING or LSState.STOPPED.

You can also use the shortcut member optimized_objective

Parameters

obj_index (int) – Index of the optimized objective

LSPhase.get_optimized_objective(obj_index)

Gets the index of the optimized objective.

You can also use the shortcut member optimized_objective

Returns

Index of the optimized objective.

Return type

int

LSPhase.set_enabled(enabled)

Sets the enabled status of this phase. The solver only optimize enabled phases. Disabling a phase can be useful when an objective has been removed from the model by LSModel.remove_objective(). By default, a phase is enabled. Only allowed in states LSState.MODELING or LSState.STOPPED.

You can also use the shortcut member enabled

Parameters

enabled (bool) – True to enable the phase, False to disable it

Since

5.0

LSPhase.is_enabled()

Returns true if the phase is enabled, False otherwise.

You can also use the shortcut member enabled

Returns

True if phase is enabled

Return type

bool

Since

5.0

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.

LSPhase.time_limit

Time limit of this phase in seconds. It is a shortcut for get_time_limit() and set_time_limit().

LSPhase.iteration_limit

Iteration limit of this phase. It is a shortcut for get_iteration_limit() and set_iteration_limit().

LSPhase.optimized_objective

Index of the optimized objective of this phase. It is a shortcut for get_optimized_objective() and set_optimized_objective().

LSPhase.enabled

Enabled status of this phase. It is a shortcut for is_enabled() and set_enabled().

Special operators and methods

LSPhase.__str__()

Returns a string representation of this phase. Useful for debugging or logging purposes.

Returns

String representation of this phase.

Return type

str