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.

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¶

Methods¶
`SetTimeLimit`	Sets the time limit of this phase in seconds.
`GetTimeLimit`	Gets the time limit of this phase in seconds.
`SetIterationLimit`	Sets the number of iterations of this phase.
`GetIterationLimit`	Gets the number of iterations of this phase.
`SetOptimizedObjective`	Sets the optimized objective of this phase.
`GetOptimizedObjective`	Gets the index of the optimized objective.
`SetEnabled`	Sets the enabled status of this phase.
`IsEnabled`	Returns true if the phase is enabled, False otherwise.
`ToString`	Returns a string representation of this phase.

Instance methods¶

void 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 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 state 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.

Arguments:	timeLimit (int) – Time limit in seconds.

int GetTimeLimit()¶

Gets the time limit of this phase in seconds. Only allowed in states Paused or Stopped.

Returns:	Time limit in seconds.
See:	LSPhase.SetTimeLimit

void SetIterationLimit(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 state 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.

Arguments:	iterationLimit (long) – Iteration limit.

long GetIterationLimit()¶

Gets the number of iterations of this phase. Only allowed in states Paused or Stopped.

Returns:	Iteration limit.
See:	LSPhase.SetIterationLimit

void 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 state Stopped.

Arguments:	objectiveIndex (int) – Index of the optimized objective.

int GetOptimizedObjective()¶

Gets the index of the optimized objective. Only allowed in states Paused or Stopped.

Returns:	Index of the optimized objective.
See:	LSPhase.SetOptimizedObjective

void 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(int). By default, a phase is enabled. Only allowed in state Stopped.

Since:	5.0
Arguments:	enabled (bool) – True to enable the phase, False to disable it.

bool IsEnabled()¶

Returns true if the phase is enabled, False otherwise. Only allowed in states Paused or Stopped.

Since:	5.0
Returns:	True if phase is enabled

string ToString()¶

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

Returns:	String representation.