Using CPLEX in TspIpSolver First, we need to set up the objective and the degree constraints. First, will add the following fields to the class so we can easily reference our problem data from any method. Add Code Block |
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private EnumSet<Option> options;
private IloCplex cplex;
private TspInstance<V,E> tspInstance;
private ImmutableBiMap<E,IloIntVar> edgeVariables;
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and initialize them, as below. Code Block |
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public TspIpSolver(TspInstance<V,E> tspInstance, EnumSet<Option> options) throws IloException{
this.options = options;
this.tspInstance = tspInstance;
this.cplex = new IloCplex();
UndirectedGraph<V,E> graph = tspInstance.getGraph(); //for convenience, we will be using this a lot
this.edgeVariables = Util.makeBinaryVariables(cplex, graph.getEdges());
//the degree constraints
//the objective
}
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The constraints and objective still need to be added to the cplex objectNext, we need to add the objective and the degree constraints to the IloCplex instance. Try adding them yourself! The following methods (as defined in Solver Specification and Java Style for CPLEX) should be useful for making the degree constraints: - From
Util , the static method integerSum(IloCplex cplex, BiMap<T,IloIntVar> variables, Iterable<T> set) - From
IloCplex , the method addEq(IloNumExpr e, double v) - From
UndirectedGraph<V,E> , the method getIncidentEdges(V vertex) If you are unfamiliar with Java, consider viewing the solution for the constraint, then trying the objective yourself. Solution Cloak |
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visible | false |
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id | ConstraintsSolution |
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For the objective, we need the functions: - From
Util , the static method sum(IloCplex cplex, BiMap<T,IloIntVar> variables, Iterable<T> set, Function<? super T,? extends Number> coefficients) - From
UndirectedGraph<V,E> , the method getEdges() - From
TspInstance , the method getEdgeWeights Solution Cloak |
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visible | false |
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id | ObjectiveSolution |
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Solving and Extracting the Solution |