multiobj_c.c
/*版权2023,Gurobi Opt狗万app足彩imization, LLC */ /*希望涵盖三个不同的集，但受允许使用*元素的共同预算的限制。然而，这些集合有不同的优先级*要覆盖;我们通过多目标优化来解决这个问题。*/ #include #include #include #include #include "gurobi_c.h" #define MAXSTR 128 int main(void) {GRBenv *env = NULL;GRBenv *menv = NULL;GRBmodel *model = NULL;Int错误= 0;int *cind = NULL;double *cval = NULL;字符缓冲区(MAXSTR); int e, i, status, nSolutions; double objn; /* Sample data */ const int groundSetSize = 20; const int nSubsets = 4; const int Budget = 12; double Set[][20] = { { 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }, { 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1 }, { 0, 0, 0, 1, 1, 0, 1, 1, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 0, 0 }, { 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 0 } }; int SetObjPriority[] = {3, 2, 2, 1}; double SetObjWeight[] = {1.0, 0.25, 1.25, 1.0}; /* Create environment */ error = GRBloadenv(&env, "multiobj_c.log"); if (error) goto QUIT; /* Create initial model */ error = GRBnewmodel(env, &model, "multiobj_c", groundSetSize, NULL, NULL, NULL, NULL, NULL); if (error) goto QUIT; /* get model environment */ menv = GRBgetenv(model); if (!menv) { fprintf(stderr, "Error: could not get model environment\n"); goto QUIT; } /* Initialize decision variables for ground set: * x[e] == 1 if element e is chosen for the covering. */ for (e = 0; e < groundSetSize; e++) { sprintf(buffer, "El%d", e); error = GRBsetcharattrelement(model, "VType", e, GRB_BINARY); if (error) goto QUIT; error = GRBsetstrattrelement(model, "VarName", e, buffer); if (error) goto QUIT; } /* Make space for constraint data */ cind = malloc(sizeof(int) * groundSetSize); if (!cind) goto QUIT; cval = malloc(sizeof(double) * groundSetSize); if (!cval) goto QUIT; /* Constraint: limit total number of elements to be picked to be at most * Budget */ for (e = 0; e < groundSetSize; e++) { cind[e] = e; cval[e] = 1.0; } sprintf (buffer, "Budget"); error = GRBaddconstr(model, groundSetSize, cind, cval, GRB_LESS_EQUAL, (double)Budget, buffer); if (error) goto QUIT; /* Set global sense for ALL objectives */ error = GRBsetintattr(model, GRB_INT_ATTR_MODELSENSE, GRB_MAXIMIZE); if (error) goto QUIT; /* Limit how many solutions to collect */ error = GRBsetintparam(menv, GRB_INT_PAR_POOLSOLUTIONS, 100); if (error) goto QUIT; /* Set and configure i-th objective */ for (i = 0; i < nSubsets; i++) { sprintf(buffer, "Set%d", i+1); error = GRBsetobjectiven(model, i, SetObjPriority[i], SetObjWeight[i], 1.0 + i, 0.01, buffer, 0.0, groundSetSize, cind, Set[i]); if (error) goto QUIT; } /* Save problem */ error = GRBwrite(model, "multiobj_c.lp"); if (error) goto QUIT; error = GRBwrite(model, "multiobj_c.mps"); if (error) goto QUIT; /* Optimize */ error = GRBoptimize(model); if (error) goto QUIT; /* Status checking */ error = GRBgetintattr(model, "Status", &status); if (error) goto QUIT; if (status == GRB_INF_OR_UNBD || status == GRB_INFEASIBLE || status == GRB_UNBOUNDED ) { printf("The model cannot be solved " "because it is infeasible or unbounded\n"); goto QUIT; } if (status != GRB_OPTIMAL) { printf("Optimization was stopped with status %i\n", status); goto QUIT; } /* Print best selected set */ error = GRBgetdblattrarray(model, GRB_DBL_ATTR_X, 0, groundSetSize, cval); if (error) goto QUIT; printf("Selected elements in best solution:\n\t"); for (e = 0; e < groundSetSize; e++) { if (cval[e] < .9) continue; printf("El%d ", e); } /* Print number of solutions stored */ error = GRBgetintattr(model, GRB_INT_ATTR_SOLCOUNT, &nSolutions); if (error) goto QUIT; printf("\nNumber of solutions found: %d\n", nSolutions); /* Print objective values of solutions */ if (nSolutions > 10) nSolutions = 10; printf("Objective values for first %d solutions:\n", nSolutions); for (i = 0; i < nSubsets; i++) { error = GRBsetintparam(menv, GRB_INT_PAR_OBJNUMBER, i); if (error) goto QUIT; printf("\tSet %d:", i); for (e = 0; e < nSolutions; e++) { error = GRBsetintparam(menv, GRB_INT_PAR_SOLUTIONNUMBER, e); if (error) goto QUIT; error = GRBgetdblattr(model, GRB_DBL_ATTR_OBJNVAL, &objn); if (error) goto QUIT; printf(" %6g", objn); } printf("\n"); } QUIT: if (cind != NULL) free(cind); if (cval != NULL) free(cval); if (model != NULL) GRBfreemodel(model); if (env != NULL) GRBfreeenv(env); return error; }
