/* glpnet04.c (grid-like network problem generator) */ /*********************************************************************** * This code is part of GLPK (GNU Linear Programming Kit). * * This code is a modified version of the program GRIDGEN, a grid-like * network problem generator developed by Yusin Lee and Jim Orlin. * The original code is publically available on the DIMACS ftp site at: * . * * All changes concern only the program interface, so this modified * version produces exactly the same instances as the original version. * * Changes were made by Andrew Makhorin . * * GLPK is free software: you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * GLPK is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public * License for more details. * * You should have received a copy of the GNU General Public License * along with GLPK. If not, see . ***********************************************************************/ #include "glpenv.h" #include "glpk.h" /*********************************************************************** * NAME * * glp_gridgen - grid-like network problem generator * * SYNOPSIS * * int glp_gridgen(glp_graph *G, int v_rhs, int a_cap, int a_cost, * const int parm[1+14]); * * DESCRIPTION * * The routine glp_gridgen is a grid-like network problem generator * developed by Yusin Lee and Jim Orlin. * * The parameter G specifies the graph object, to which the generated * problem data have to be stored. Note that on entry the graph object * is erased with the routine glp_erase_graph. * * The parameter v_rhs specifies an offset of the field of type double * in the vertex data block, to which the routine stores the supply or * demand value. If v_rhs < 0, the value is not stored. * * The parameter a_cap specifies an offset of the field of type double * in the arc data block, to which the routine stores the arc capacity. * If a_cap < 0, the capacity is not stored. * * The parameter a_cost specifies an offset of the field of type double * in the arc data block, to which the routine stores the per-unit cost * if the arc flow. If a_cost < 0, the cost is not stored. * * The array parm contains description of the network to be generated: * * parm[0] not used * parm[1] two-ways arcs indicator: * 1 - if links in both direction should be generated * 0 - otherwise * parm[2] random number seed (a positive integer) * parm[3] number of nodes (the number of nodes generated might be * slightly different to make the network a grid) * parm[4] grid width * parm[5] number of sources * parm[6] number of sinks * parm[7] average degree * parm[8] total flow * parm[9] distribution of arc costs: * 1 - uniform * 2 - exponential * parm[10] lower bound for arc cost (uniform) * 100 * lambda (exponential) * parm[11] upper bound for arc cost (uniform) * not used (exponential) * parm[12] distribution of arc capacities: * 1 - uniform * 2 - exponential * parm[13] lower bound for arc capacity (uniform) * 100 * lambda (exponential) * parm[14] upper bound for arc capacity (uniform) * not used (exponential) * * RETURNS * * If the instance was successfully generated, the routine glp_gridgen * returns zero; otherwise, if specified parameters are inconsistent, * the routine returns a non-zero error code. * * COMMENTS * * This network generator generates a grid-like network plus a super * node. In additional to the arcs connecting the nodes in the grid, * there is an arc from each supply node to the super node and from the * super node to each demand node to guarantee feasiblity. These arcs * have very high costs and very big capacities. * * The idea of this network generator is as follows: First, a grid of * n1 * n2 is generated. For example, 5 * 3. The nodes are numbered as * 1 to 15, and the supernode is numbered as n1*n2+1. Then arcs between * adjacent nodes are generated. For these arcs, the user is allowed to * specify either to generate two-way arcs or one-way arcs. If two-way * arcs are to be generated, two arcs, one in each direction, will be * generated between each adjacent node pairs. Otherwise, only one arc * will be generated. If this is the case, the arcs will be generated * in alterntive directions as shown below. * * 1 ---> 2 ---> 3 ---> 4 ---> 5 * | ^ | ^ | * | | | | | * V | V | V * 6 <--- 7 <--- 8 <--- 9 <--- 10 * | ^ | ^ | * | | | | | * V | V | V * 11 --->12 --->13 --->14 ---> 15 * * Then the arcs between the super node and the source/sink nodes are * added as mentioned before. If the number of arcs still doesn't reach * the requirement, additional arcs will be added by uniformly picking * random node pairs. There is no checking to prevent multiple arcs * between any pair of nodes. However, there will be no self-arcs (arcs * that poins back to its tail node) in the network. * * The source and sink nodes are selected uniformly in the network, and * the imbalances of each source/sink node are also assigned by uniform * distribution. */ struct stat_para { /* structure for statistical distributions */ int distribution; /* the distribution: */ #define UNIFORM 1 /* uniform distribution */ #define EXPONENTIAL 2 /* exponential distribution */ double parameter[5]; /* the parameters of the distribution */ }; struct arcs { int from; /* the FROM node of that arc */ int to; /* the TO node of that arc */ int cost; /* original cost of that arc */ int u; /* capacity of the arc */ }; struct imbalance { int node; /* Node ID */ int supply; /* Supply of that node */ }; struct csa { /* common storage area */ glp_graph *G; int v_rhs, a_cap, a_cost; int seed; /* random number seed */ int seed_original; /* the original seed from input */ int two_way; /* 0: generate arcs in both direction for the basic grid, except for the arcs to/from the super node. 1: o/w */ int n_node; /* total number of nodes in the network, numbered 1 to n_node, including the super node, which is the last one */ int n_arc; /* total number of arcs in the network, counting EVERY arc. */ int n_grid_arc; /* number of arcs in the basic grid, including the arcs to/from the super node */ int n_source, n_sink; /* number of source and sink nodes */ int avg_degree; /* average degree, arcs to and from the super node are counted */ int t_supply; /* total supply in the network */ int n1, n2; /* the two edges of the network grid. n1 >= n2 */ struct imbalance *source_list, *sink_list; /* head of the array of source/sink nodes */ struct stat_para arc_costs; /* the distribution of arc costs */ struct stat_para capacities; /* distribution of the capacities of the arcs */ struct arcs *arc_list; /* head of the arc list array. Arcs in this array are in the order of grid_arcs, arcs to/from super node, and other arcs */ }; #define G (csa->G) #define v_rhs (csa->v_rhs) #define a_cap (csa->a_cap) #define a_cost (csa->a_cost) #define seed (csa->seed) #define seed_original (csa->seed_original) #define two_way (csa->two_way) #define n_node (csa->n_node) #define n_arc (csa->n_arc) #define n_grid_arc (csa->n_grid_arc) #define n_source (csa->n_source) #define n_sink (csa->n_sink) #define avg_degree (csa->avg_degree) #define t_supply (csa->t_supply) #define n1 (csa->n1) #define n2 (csa->n2) #define source_list (csa->source_list) #define sink_list (csa->sink_list) #define arc_costs (csa->arc_costs) #define capacities (csa->capacities) #define arc_list (csa->arc_list) static void assign_capacities(struct csa *csa); static void assign_costs(struct csa *csa); static void assign_imbalance(struct csa *csa); static int exponential(struct csa *csa, double lambda[1]); static struct arcs *gen_additional_arcs(struct csa *csa, struct arcs *arc_ptr); static struct arcs *gen_basic_grid(struct csa *csa, struct arcs *arc_ptr); static void gen_more_arcs(struct csa *csa, struct arcs *arc_ptr); static void generate(struct csa *csa); static void output(struct csa *csa); static double randy(struct csa *csa); static void select_source_sinks(struct csa *csa); static int uniform(struct csa *csa, double a[2]); int glp_gridgen(glp_graph *G_, int _v_rhs, int _a_cap, int _a_cost, const int parm[1+14]) { struct csa _csa, *csa = &_csa; int n, ret; G = G_; v_rhs = _v_rhs; a_cap = _a_cap; a_cost = _a_cost; if (G != NULL) { if (v_rhs >= 0 && v_rhs > G->v_size - (int)sizeof(double)) xerror("glp_gridgen: v_rhs = %d; invalid offset\n", v_rhs); if (a_cap >= 0 && a_cap > G->a_size - (int)sizeof(double)) xerror("glp_gridgen: a_cap = %d; invalid offset\n", a_cap); if (a_cost >= 0 && a_cost > G->a_size - (int)sizeof(double)) xerror("glp_gridgen: a_cost = %d; invalid offset\n", a_cost) ; } /* Check the parameters for consistency. */ if (!(parm[1] == 0 || parm[1] == 1)) { ret = 1; goto done; } if (parm[2] < 1) { ret = 2; goto done; } if (!(10 <= parm[3] && parm[3] <= 40000)) { ret = 3; goto done; } if (!(1 <= parm[4] && parm[4] <= 40000)) { ret = 4; goto done; } if (!(parm[5] >= 0 && parm[6] >= 0 && parm[5] + parm[6] <= parm[3])) { ret = 5; goto done; } if (!(1 <= parm[7] && parm[7] <= parm[3])) { ret = 6; goto done; } if (parm[8] < 0) { ret = 7; goto done; } if (!(parm[9] == 1 || parm[9] == 2)) { ret = 8; goto done; } if (parm[9] == 1 && parm[10] > parm[11] || parm[9] == 2 && parm[10] < 1) { ret = 9; goto done; } if (!(parm[12] == 1 || parm[12] == 2)) { ret = 10; goto done; } if (parm[12] == 1 && !(0 <= parm[13] && parm[13] <= parm[14]) || parm[12] == 2 && parm[13] < 1) { ret = 11; goto done; } /* Initialize the graph object. */ if (G != NULL) { glp_erase_graph(G, G->v_size, G->a_size); glp_set_graph_name(G, "GRIDGEN"); } /* Copy the generator parameters. */ two_way = parm[1]; seed_original = seed = parm[2]; n_node = parm[3]; n = parm[4]; n_source = parm[5]; n_sink = parm[6]; avg_degree = parm[7]; t_supply = parm[8]; arc_costs.distribution = parm[9]; if (parm[9] == 1) { arc_costs.parameter[0] = parm[10]; arc_costs.parameter[1] = parm[11]; } else { arc_costs.parameter[0] = (double)parm[10] / 100.0; arc_costs.parameter[1] = 0.0; } capacities.distribution = parm[12]; if (parm[12] == 1) { capacities.parameter[0] = parm[13]; capacities.parameter[1] = parm[14]; } else { capacities.parameter[0] = (double)parm[13] / 100.0; capacities.parameter[1] = 0.0; } /* Calculate the edge lengths of the grid according to the input. */ if (n * n >= n_node) { n1 = n; n2 = (int)((double)n_node / (double)n + 0.5); } else { n2 = n; n1 = (int)((double)n_node / (double)n + 0.5); } /* Recalculate the total number of nodes and plus 1 for the super node. */ n_node = n1 * n2 + 1; n_arc = n_node * avg_degree; n_grid_arc = (two_way + 1) * ((n1 - 1) * n2 + (n2 - 1) * n1) + n_source + n_sink; if (n_grid_arc > n_arc) n_arc = n_grid_arc; arc_list = xcalloc(n_arc, sizeof(struct arcs)); source_list = xcalloc(n_source, sizeof(struct imbalance)); sink_list = xcalloc(n_sink, sizeof(struct imbalance)); /* Generate a random network. */ generate(csa); /* Output the network. */ output(csa); /* Free all allocated memory. */ xfree(arc_list); xfree(source_list); xfree(sink_list); /* The instance has been successfully generated. */ ret = 0; done: return ret; } #undef random static void assign_capacities(struct csa *csa) { /* Assign a capacity to each arc. */ struct arcs *arc_ptr = arc_list; int (*random)(struct csa *csa, double *); int i; /* Determine the random number generator to use. */ switch (arc_costs.distribution) { case UNIFORM: random = uniform; break; case EXPONENTIAL: random = exponential; break; default: xassert(csa != csa); } /* Assign capacities to grid arcs. */ for (i = n_source + n_sink; i < n_grid_arc; i++, arc_ptr++) arc_ptr->u = random(csa, capacities.parameter); i = i - n_source - n_sink; /* Assign capacities to arcs to/from supernode. */ for (; i < n_grid_arc; i++, arc_ptr++) arc_ptr->u = t_supply; /* Assign capacities to all other arcs. */ for (; i < n_arc; i++, arc_ptr++) arc_ptr->u = random(csa, capacities.parameter); return; } static void assign_costs(struct csa *csa) { /* Assign a cost to each arc. */ struct arcs *arc_ptr = arc_list; int (*random)(struct csa *csa, double *); int i; /* A high cost assigned to arcs to/from the supernode. */ int high_cost; /* The maximum cost assigned to arcs in the base grid. */ int max_cost = 0; /* Determine the random number generator to use. */ switch (arc_costs.distribution) { case UNIFORM: random = uniform; break; case EXPONENTIAL: random = exponential; break; default: xassert(csa != csa); } /* Assign costs to arcs in the base grid. */ for (i = n_source + n_sink; i < n_grid_arc; i++, arc_ptr++) { arc_ptr->cost = random(csa, arc_costs.parameter); if (max_cost < arc_ptr->cost) max_cost = arc_ptr->cost; } i = i - n_source - n_sink; /* Assign costs to arcs to/from the super node. */ high_cost = max_cost * 2; for (; i < n_grid_arc; i++, arc_ptr++) arc_ptr->cost = high_cost; /* Assign costs to all other arcs. */ for (; i < n_arc; i++, arc_ptr++) arc_ptr->cost = random(csa, arc_costs.parameter); return; } static void assign_imbalance(struct csa *csa) { /* Assign an imbalance to each node. */ int total, i; double avg; struct imbalance *ptr; /* assign the supply nodes */ avg = 2.0 * t_supply / n_source; do { for (i = 1, total = t_supply, ptr = source_list + 1; i < n_source; i++, ptr++) { ptr->supply = (int)(randy(csa) * avg + 0.5); total -= ptr->supply; } source_list->supply = total; } /* redo all if the assignment "overshooted" */ while (total <= 0); /* assign the demand nodes */ avg = -2.0 * t_supply / n_sink; do { for (i = 1, total = t_supply, ptr = sink_list + 1; i < n_sink; i++, ptr++) { ptr->supply = (int)(randy(csa) * avg - 0.5); total += ptr->supply; } sink_list->supply = - total; } while (total <= 0); return; } static int exponential(struct csa *csa, double lambda[1]) { /* Returns an "exponentially distributed" integer with parameter lambda. */ return ((int)(- lambda[0] * log((double)randy(csa)) + 0.5)); } static struct arcs *gen_additional_arcs(struct csa *csa, struct arcs *arc_ptr) { /* Generate an arc from each source to the supernode and from supernode to each sink. */ int i; for (i = 0; i < n_source; i++, arc_ptr++) { arc_ptr->from = source_list[i].node; arc_ptr->to = n_node; } for (i = 0; i < n_sink; i++, arc_ptr++) { arc_ptr->to = sink_list[i].node; arc_ptr->from = n_node; } return arc_ptr; } static struct arcs *gen_basic_grid(struct csa *csa, struct arcs *arc_ptr) { /* Generate the basic grid. */ int direction = 1, i, j, k; if (two_way) { /* Generate an arc in each direction. */ for (i = 1; i < n_node; i += n1) { for (j = i, k = j + n1 - 1; j < k; j++) { arc_ptr->from = j; arc_ptr->to = j + 1; arc_ptr++; arc_ptr->from = j + 1; arc_ptr->to = j; arc_ptr++; } } for (i = 1; i <= n1; i++) { for (j = i + n1; j < n_node; j += n1) { arc_ptr->from = j; arc_ptr->to = j - n1; arc_ptr++; arc_ptr->from = j - n1; arc_ptr->to = j; arc_ptr++; } } } else { /* Generate one arc in each direction. */ for (i = 1; i < n_node; i += n1) { if (direction == 1) j = i; else j = i + 1; for (k = j + n1 - 1; j < k; j++) { arc_ptr->from = j; arc_ptr->to = j + direction; arc_ptr++; } direction = - direction; } for (i = 1; i <= n1; i++) { j = i + n1; if (direction == 1) { for (; j < n_node; j += n1) { arc_ptr->from = j - n1; arc_ptr->to = j; arc_ptr++; } } else { for (; j < n_node; j += n1) { arc_ptr->from = j - n1; arc_ptr->to = j; arc_ptr++; } } direction = - direction; } } return arc_ptr; } static void gen_more_arcs(struct csa *csa, struct arcs *arc_ptr) { /* Generate random arcs to meet the specified density. */ int i; double ab[2]; ab[0] = 0.9; ab[1] = n_node - 0.99; /* upper limit is n_node-1 because the supernode cannot be selected */ for (i = n_grid_arc; i < n_arc; i++, arc_ptr++) { arc_ptr->from = uniform(csa, ab); arc_ptr->to = uniform(csa, ab); if (arc_ptr->from == arc_ptr->to) { arc_ptr--; i--; } } return; } static void generate(struct csa *csa) { /* Generate a random network. */ struct arcs *arc_ptr = arc_list; arc_ptr = gen_basic_grid(csa, arc_ptr); select_source_sinks(csa); arc_ptr = gen_additional_arcs(csa, arc_ptr); gen_more_arcs(csa, arc_ptr); assign_costs(csa); assign_capacities(csa); assign_imbalance(csa); return; } static void output(struct csa *csa) { /* Output the network in DIMACS format. */ struct arcs *arc_ptr; struct imbalance *imb_ptr; int i; if (G != NULL) goto skip; /* Output "c", "p" records. */ xprintf("c generated by GRIDGEN\n"); xprintf("c seed %d\n", seed_original); xprintf("c nodes %d\n", n_node); xprintf("c grid size %d X %d\n", n1, n2); xprintf("c sources %d sinks %d\n", n_source, n_sink); xprintf("c avg. degree %d\n", avg_degree); xprintf("c supply %d\n", t_supply); switch (arc_costs.distribution) { case UNIFORM: xprintf("c arc costs: UNIFORM distr. min %d max %d\n", (int)arc_costs.parameter[0], (int)arc_costs.parameter[1]); break; case EXPONENTIAL: xprintf("c arc costs: EXPONENTIAL distr. lambda %d\n", (int)arc_costs.parameter[0]); break; default: xassert(csa != csa); } switch (capacities.distribution) { case UNIFORM: xprintf("c arc caps : UNIFORM distr. min %d max %d\n", (int)capacities.parameter[0], (int)capacities.parameter[1]); break; case EXPONENTIAL: xprintf("c arc caps : EXPONENTIAL distr. %d lambda %d\n", (int)capacities.parameter[0]); break; default: xassert(csa != csa); } skip: if (G == NULL) xprintf("p min %d %d\n", n_node, n_arc); else { glp_add_vertices(G, n_node); if (v_rhs >= 0) { double zero = 0.0; for (i = 1; i <= n_node; i++) { glp_vertex *v = G->v[i]; memcpy((char *)v->data + v_rhs, &zero, sizeof(double)); } } } /* Output "n node supply". */ for (i = 0, imb_ptr = source_list; i < n_source; i++, imb_ptr++) { if (G == NULL) xprintf("n %d %d\n", imb_ptr->node, imb_ptr->supply); else { if (v_rhs >= 0) { double temp = (double)imb_ptr->supply; glp_vertex *v = G->v[imb_ptr->node]; memcpy((char *)v->data + v_rhs, &temp, sizeof(double)); } } } for (i = 0, imb_ptr = sink_list; i < n_sink; i++, imb_ptr++) { if (G == NULL) xprintf("n %d %d\n", imb_ptr->node, imb_ptr->supply); else { if (v_rhs >= 0) { double temp = (double)imb_ptr->supply; glp_vertex *v = G->v[imb_ptr->node]; memcpy((char *)v->data + v_rhs, &temp, sizeof(double)); } } } /* Output "a from to lowcap=0 hicap cost". */ for (i = 0, arc_ptr = arc_list; i < n_arc; i++, arc_ptr++) { if (G == NULL) xprintf("a %d %d 0 %d %d\n", arc_ptr->from, arc_ptr->to, arc_ptr->u, arc_ptr->cost); else { glp_arc *a = glp_add_arc(G, arc_ptr->from, arc_ptr->to); if (a_cap >= 0) { double temp = (double)arc_ptr->u; memcpy((char *)a->data + a_cap, &temp, sizeof(double)); } if (a_cost >= 0) { double temp = (double)arc_ptr->cost; memcpy((char *)a->data + a_cost, &temp, sizeof(double)); } } } return; } static double randy(struct csa *csa) { /* Returns a random number between 0.0 and 1.0. See Ward Cheney & David Kincaid, "Numerical Mathematics and Computing," 2Ed, pp. 335. */ seed = 16807 * seed % 2147483647; if (seed < 0) seed = - seed; return seed * 4.6566128752459e-10; } static void select_source_sinks(struct csa *csa) { /* Randomly select the source nodes and sink nodes. */ int i, *int_ptr; int *temp_list; /* a temporary list of nodes */ struct imbalance *ptr; double ab[2]; /* parameter for random number generator */ ab[0] = 0.9; ab[1] = n_node - 0.99; /* upper limit is n_node-1 because the supernode cannot be selected */ temp_list = xcalloc(n_node, sizeof(int)); for (i = 0, int_ptr = temp_list; i < n_node; i++, int_ptr++) *int_ptr = 0; /* Select the source nodes. */ for (i = 0, ptr = source_list; i < n_source; i++, ptr++) { ptr->node = uniform(csa, ab); if (temp_list[ptr->node] == 1) /* check for duplicates */ { ptr--; i--; } else temp_list[ptr->node] = 1; } /* Select the sink nodes. */ for (i = 0, ptr = sink_list; i < n_sink; i++, ptr++) { ptr->node = uniform(csa, ab); if (temp_list[ptr->node] == 1) { ptr--; i--; } else temp_list[ptr->node] = 1; } xfree(temp_list); return; } int uniform(struct csa *csa, double a[2]) { /* Generates an integer uniformly selected from [a[0],a[1]]. */ return (int)((a[1] - a[0]) * randy(csa) + a[0] + 0.5); } /**********************************************************************/ #if 0 int main(void) { int parm[1+14]; double temp; scanf("%d", &parm[1]); scanf("%d", &parm[2]); scanf("%d", &parm[3]); scanf("%d", &parm[4]); scanf("%d", &parm[5]); scanf("%d", &parm[6]); scanf("%d", &parm[7]); scanf("%d", &parm[8]); scanf("%d", &parm[9]); if (parm[9] == 1) { scanf("%d", &parm[10]); scanf("%d", &parm[11]); } else { scanf("%le", &temp); parm[10] = (int)(100.0 * temp + .5); parm[11] = 0; } scanf("%d", &parm[12]); if (parm[12] == 1) { scanf("%d", &parm[13]); scanf("%d", &parm[14]); } else { scanf("%le", &temp); parm[13] = (int)(100.0 * temp + .5); parm[14] = 0; } glp_gridgen(NULL, 0, 0, 0, parm); return 0; } #endif /* eof */