Filtering the Solution Pool

ILOG CPLEX 11.0 User's Manual > Discrete Optimization > Solution Pool: Generating and Keeping Multiple Solutions > Filtering the Solution Pool

Filtering the Solution Pool

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Filtering allows you to control properties of the solutions generated and stored in the solution pool. ILOG CPLEX provides two predefined ways to filter solutions.

If you want to filter solutions based on their difference as compared to a reference solution, use a diversity filter, as explained in Diversity Filters.
If you want to filter solutions based on their validity in an additional linear constraint, use a range filter, as explained in Range Filters.

Those two ways are practical for most purposes. However, if you require finer control of which solutions to keep and which to eliminate, use an incumbent callback, as explained in Incumbent Callback as a Filter.

Adding or deleting filters does not affect the solutions already in the pool; new filters are applied only at the next call of MIP optimization or the populate procedure.

Filters are assigned an index number when they are added to the solution pool, and they may be accessed through this index number. Diversity filters and range filters share the same sequence of indices.

To count the number of filters associated with the solution pool, use one of these methods, routines, or commands:

In Concert Technology

IloCplex::getNfilters in the C++ API;
IloCplex.getNFilters in the Java API;
Cplex.GetNFilters in the .NET API.

CPXgetsolnpoolnumfilters in the Callable Library (C API );

To access a filter, use one of these methods, routines, or commands:

Concert Technology offers a method to access each characteristic of a filter; for example, getFilterType, getFilterIndex, getFilterVars, and so forth.
CPXgetsolnpoolrngfilter or CPXgetsolnpooldivfilter in the C API;

To delete a filter, use one of these methods, routines, or commands:

In Concert Technology

In the C++ API, use the method IloCplex::delFilter.
In the Java API, use the method IloCplex.delFilter.
In the .NET API, use the method Cplex.DelFilter.

In the Callable Library (C API), use CPXdelsolnpoolfilters .
In the Interactive Optimizer, use the command change delete filter.

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