Callbacks

CallbackModel

The callback model to interact with the algorithm during the callback function.

Use setCallback to set a callback function. The callback function will be invoked with an initialized callback model.

convexDual: float property

The convex dual value for a subproblem.

Returns:

Type	Description
float	A list with values for all variables.

Note

Only valid in PathMIPSubproblem.

dominanceType: DominanceType property

The current graph index.

Returns:

Type	Description
DominanceType	The graph id.

edge: int property

The current edge in the graph on which extension of state is happening.

Returns:

Type	Description
int	The edge id.

Note

Only valid in DPExtend.

haveArtificialCost: bool property

Verify if the edge costs are artifical. This happens when the path MIP attempts to restore feasibility. Correct costs are recalculated when feasiblity is restored.

If the path cost have non-edge components, like resource dependent non-linear costs, those must be skipped when calculating artificial reduced costs.

Returns:

Type	Description
bool	A boolean flag indicating if edge cost is artificial.

Note

Only applicable in the dynamic programming algorithm when solving a path MIP.

k: int property

The current graph index.

Returns:

Type	Description
int	The graph id.

reducedCost: List[float] property

The current reduced cost for a subproblem.

Access k to get information of the current subproblem and use convexDual to get the current convex dual value.

Returns:

Type	Description
List[float]	A list with values for all variables.

Note

Only valid in PathMIPSubproblem.

vertex: int property

The current vertex in the graph.

Returns:

Type	Description
int	The vertex id.

Note

Only applicable in the dynamic programming algorithm.

x: List[float] property

The current variable values.

• For PathMIPCuts or PathMIPHeuristic it is the current relaxation
• For PathMIPSolution it is a solution candidate.

Returns:

Type	Description
List[float]	A list with values for all variables.

Note

Only valid in PathMIPCuts,

PathMIPHeuristic, or PathMIPSolution.

zeroEdges: List[int] property

The current list of edges with values fixed to zero.

Returns:

Type	Description
List[int]	A list of edge indices.

Note

Only valid in PathMIPSubproblem.

addCut(equa)

Add a cut to the model.

Parameters:

Name	Type	Description	Default
equa	LinEqua	The cut as a linear equation.	required

Note

Only valid in PathMIPCuts

addPath(cost, eids)

Add a path to a subproblem during initialization.

Parameters:

Name	Type	Description	Default
cost	float	The cost of the path.	required
eids	List[int]	A list of edge indices.	required

Note

Only valid in PathMIPInit.

addPathReducedCost(reducedCost, cost, eids)

Add a path to a subproblem if using a custom subproblem algorithm.

Parameters:

Name	Type	Description	Default
reducedCost	float	The reduced cost of the path.	required
cost	float	The cost of the path.	required
eids	List[int]	A list of edge indices.	required

Note

Only valid in PathMIPSubproblem.

addSolution(cost, x)

Add a solution to the problem.

Parameters:

Name	Type	Description	Default
cost	float	The objective value of the solution.	required
x	List[float]	A list of variable values.	required

Note

Only valid in PathMIPHeuristic.

getResource(name)

Get the current resource value.

Parameters:

Name	Type	Description	Default
name	str	The name of the resource.	required

Returns:

Type	Description
float	The resource value.

Note

Only applicable in the dynamic programming algorithm.

getResourceOther(name)

Get the current resource of another label in dominance.

Parameters:

Name	Type	Description	Default
name	str	The name of the resource.	required

Returns:

Type	Description
float	The resource value of the other label.

Note

Only valid in DPDominate.

keep()

Indicate that the label under consideration to be dominated should be kept. That is, if the other label is not dominated then this function should be invoked.

Note

Only valid in DPDominate

setResource(name, value)

Set the current resource value.

Parameters:

Name	Type	Description	Default
name	str	The name of the resource.	required
value	float	The new value to set.	required

Note

Only applicable in the dynamic programming algorithm.

setStatus(status)

Set the optimization status if using a custom subproblem algorithm.

Parameters:

Name	Type	Description	Default
status	OptimizationStatus	The optimization status	required

Note

Only valid in PathMIPSubproblem.

skip()

Invoking this function has different meanings depending on Where:

In the dynamic programming algorithm

• For DPExtend then discard a label if it is infeasible.

In the path MIP algorithm

• For PathMIPSolution then skip a solution if is infeasible.
• For PathMIPSubproblem then skip calls to the internal dynamic programming algorithm. Only paths added with addPath are then present in the path MIP.

Note

Only valid in DPExtend, PathMIPSolution, or PathMIPSubproblem.