LSPhase Class¶

class 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.

At least one phase must be created to launch the solver. If you have only one objective to optimize, then create a phase, set the time or the number of iterations, and run the solver. By default, the optimized objective of a phase corresponds to the last objective declared in the model (in this case, all objectives of the model are optimized together).

Summary¶

Functions¶

void LSPhase::setTimeLimit(int timeLimit)¶

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 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 S_Modeling or S_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.

Parameters: timeLimit – Time limit in seconds.

int LSPhase::getTimeLimit() const¶

Gets the time limit of this phase in seconds.

Returns: Time limit in seconds.
See: LSPhase::setTimeLimit()

void LSPhase::setIterationLimit(long long iterationLimit)¶

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 S_Modeling or S_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.

Parameters: iterationLimit – Iteration limit.

long long LSPhase::getIterationLimit() const¶

Gets the number of iterations of this phase.

Returns: Iteration limit.
See: LSPhase::setIterationLimit()

void LSPhase::setOptimizedObjective(int objectiveIndex)¶

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 S_Modeling or S_Stopped.

Parameters: objectiveIndex – Index of the optimized objective.

int LSPhase::getOptimizedObjective() const¶

Gets the index of the optimized objective.

Returns: Index of the optimized objective.
See: LSPhase::setOptimizedObjective()

void LSPhase::setEnabled(bool 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::removeObjective(). By default, a phase is enabled. Only allowed in states S_Modeling or S_Stopped.

Parameters: enabled – True to enable the phase, False to disable it
Since: 5.0

bool LSPhase::isEnabled() const¶

Returns true if the phase is enabled, False otherwise.

Returns: True if phase is enabled
Since: 5.0

std::string LSPhase::toString() const¶

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

Returns: String representation.