callback_c.c
/ *版权所有2019，Gurobi优狗万app足彩化，LLC * / / *此示例从文件中读取模型，请设置一个调用的回调，监视优化进度并实现自定义终止策略，并将进度信息输出到屏幕并向日志文件输出。在该回调中实现的终止策略停止了一旦满足以下两个条件中的至少一个条件中的至少一个：1）最佳间隙小于10％2）已经探索了至少10000个节点，并且整数已找到可行的解决方案。请注意，终止通常通过Gurobi参数（MIPGAP，Nodelimit等）处理。如果可用参数不会捕获所需的终止标准，则应仅使用回调来终止。* / #include #include #include #include“gurobi_c.h”/ *定义结构将我的数据传递给回调函数* / struct callback_data {double返回;双LastNode;双*解决方案;文件* logfile;}; /* Define my callback function */ int __stdcall mycallback(GRBmodel *model, void *cbdata, int where, void *usrdata) { struct callback_data *mydata = (struct callback_data *) usrdata; if (where == GRB_CB_POLLING) { /* Ignore polling callback */ } else if (where == GRB_CB_PRESOLVE) { /* Presolve callback */ int cdels, rdels; GRBcbget(cbdata, where, GRB_CB_PRE_COLDEL, &cdels); GRBcbget(cbdata, where, GRB_CB_PRE_ROWDEL, &rdels); if (cdels || rdels) { printf("%7d columns and %7d rows are removed\n", cdels, rdels); } } else if (where == GRB_CB_SIMPLEX) { /* Simplex callback */ double itcnt, obj, pinf, dinf; int ispert; char ch; GRBcbget(cbdata, where, GRB_CB_SPX_ITRCNT, &itcnt); if (itcnt - mydata->lastiter >= 100) { mydata->lastiter = itcnt; GRBcbget(cbdata, where, GRB_CB_SPX_OBJVAL, &obj); GRBcbget(cbdata, where, GRB_CB_SPX_ISPERT, &ispert); GRBcbget(cbdata, where, GRB_CB_SPX_PRIMINF, &pinf); GRBcbget(cbdata, where, GRB_CB_SPX_DUALINF, &dinf); if (ispert == 0) ch = ' '; else if (ispert == 1) ch = 'S'; else ch = 'P'; printf("%7.0f %14.7e%c %13.6e %13.6e\n", itcnt, obj, ch, pinf, dinf); } } else if (where == GRB_CB_MIP) { /* General MIP callback */ double nodecnt, objbst, objbnd, actnodes, itcnt; int solcnt, cutcnt; GRBcbget(cbdata, where, GRB_CB_MIP_NODCNT, &nodecnt); GRBcbget(cbdata, where, GRB_CB_MIP_OBJBST, &objbst); GRBcbget(cbdata, where, GRB_CB_MIP_OBJBND, &objbnd); GRBcbget(cbdata, where, GRB_CB_MIP_SOLCNT, &solcnt); if (nodecnt - mydata->lastnode >= 100) { mydata->lastnode = nodecnt; GRBcbget(cbdata, where, GRB_CB_MIP_NODLFT, &actnodes); GRBcbget(cbdata, where, GRB_CB_MIP_ITRCNT, &itcnt); GRBcbget(cbdata, where, GRB_CB_MIP_CUTCNT, &cutcnt); printf("%7.0f %7.0f %8.0f %13.6e %13.6e %7d %7d\n", nodecnt, actnodes, itcnt, objbst, objbnd, solcnt, cutcnt); } if (fabs(objbst - objbnd) < 0.1 * (1.0 + fabs(objbst))) { printf("Stop early - 10%% gap achieved\n"); GRBterminate(model); } if (nodecnt >= 10000 && solcnt) { printf("Stop early - 10000 nodes explored\n"); GRBterminate(model); } } else if (where == GRB_CB_MIPSOL) { /* MIP solution callback */ double nodecnt, obj; int solcnt; GRBcbget(cbdata, where, GRB_CB_MIPSOL_NODCNT, &nodecnt); GRBcbget(cbdata, where, GRB_CB_MIPSOL_OBJ, &obj); GRBcbget(cbdata, where, GRB_CB_MIPSOL_SOLCNT, &solcnt); GRBcbget(cbdata, where, GRB_CB_MIPSOL_SOL, mydata->solution); printf("**** New solution at node %.0f, obj %g, sol %d, x[0] = %.2f ****\n", nodecnt, obj, solcnt, mydata->solution[0]); } else if (where == GRB_CB_MIPNODE) { int status; /* MIP node callback */ printf("**** New node ****\n"); GRBcbget(cbdata, where, GRB_CB_MIPNODE_STATUS, &status); if (status == GRB_OPTIMAL) { GRBcbget(cbdata, where, GRB_CB_MIPNODE_REL, mydata->solution); GRBcbsolution(cbdata, mydata->solution, NULL); } } else if (where == GRB_CB_BARRIER) { /* Barrier callback */ int itcnt; double primobj, dualobj, priminf, dualinf, compl; GRBcbget(cbdata, where, GRB_CB_BARRIER_ITRCNT, &itcnt); GRBcbget(cbdata, where, GRB_CB_BARRIER_PRIMOBJ, &primobj); GRBcbget(cbdata, where, GRB_CB_BARRIER_DUALOBJ, &dualobj); GRBcbget(cbdata, where, GRB_CB_BARRIER_PRIMINF, &priminf); GRBcbget(cbdata, where, GRB_CB_BARRIER_DUALINF, &dualinf); GRBcbget(cbdata, where, GRB_CB_BARRIER_COMPL, &compl); printf("%d %.4e %.4e %.4e %.4e %.4e\n", itcnt, primobj, dualobj, priminf, dualinf, compl); } else if (where == GRB_CB_MESSAGE) { /* Message callback */ char *msg; GRBcbget(cbdata, where, GRB_CB_MSG_STRING, &msg); fprintf(mydata->logfile, "%s", msg); } return 0; } int main(int argc, char *argv[]) { GRBenv *env = NULL; GRBmodel *model = NULL; int error = 0; int numvars, solcount, optimstatus, j; double objval, x; char *varname; struct callback_data mydata; mydata.lastiter = -GRB_INFINITY; mydata.lastnode = -GRB_INFINITY; mydata.solution = NULL; mydata.logfile = NULL; if (argc < 2) { fprintf(stderr, "Usage: callback_c filename\n"); goto QUIT; } /* Open log file */ mydata.logfile = fopen("cb.log", "w"); if (!mydata.logfile) { fprintf(stderr, "Cannot open cb.log for callback message\n"); goto QUIT; } /* Create environment */ error = GRBloadenv(&env, NULL); if (error) goto QUIT; /* Turn off display and heuristics */ error = GRBsetintparam(env, GRB_INT_PAR_OUTPUTFLAG, 0); if (error) goto QUIT; error = GRBsetdblparam(env, GRB_DBL_PAR_HEURISTICS, 0.0); if (error) goto QUIT; /* Read model from file */ error = GRBreadmodel(env, argv[1], &model); if (error) goto QUIT; /* Allocate space for solution */ error = GRBgetintattr(model, GRB_INT_ATTR_NUMVARS, &numvars); if (error) goto QUIT; mydata.solution = malloc(numvars*sizeof(double)); if (mydata.solution == NULL) { fprintf(stderr, "Failed to allocate memory\n"); exit(1); } /* Set callback function */ error = GRBsetcallbackfunc(model, mycallback, (void *) &mydata); if (error) goto QUIT; /* Solve model */ error = GRBoptimize(model); if (error) goto QUIT; /* Capture solution information */ printf("\nOptimization complete\n"); error = GRBgetintattr(model, GRB_INT_ATTR_SOLCOUNT, &solcount); if (error) goto QUIT; error = GRBgetintattr(model, GRB_INT_ATTR_STATUS, &optimstatus); if (error) goto QUIT; if (solcount == 0) { printf("No solution found, optimization status = %d\n", optimstatus); goto QUIT; } error = GRBgetdblattr(model, GRB_DBL_ATTR_OBJVAL, &objval); if (error) goto QUIT; printf("Solution found, objective = %.4e\n", objval); for ( j = 0; j < numvars; ++j ) { error = GRBgetstrattrelement(model, GRB_STR_ATTR_VARNAME, j, &varname); if (error) goto QUIT; error = GRBgetdblattrelement(model, GRB_DBL_ATTR_X, j, &x); if (error) goto QUIT; if (x != 0.0) { printf("%s %f\n", varname, x); } } QUIT: /* Error reporting */ if (error) { printf("ERROR: %s\n", GRBgeterrormsg(env)); exit(1); } /* Close log file */ if (mydata.logfile) fclose(mydata.logfile); /* Free solution */ if (mydata.solution) free(mydata.solution); /* Free model */ GRBfreemodel(model); /* Free environment */ GRBfreeenv(env); return 0; }
