125 lines
2.8 KiB
C
125 lines
2.8 KiB
C
/*------------------------------------------------------------------------
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*
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* geqo_cx.c
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*
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* cycle crossover [CX] routines;
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* CX operator according to Oliver et al
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* (Proc 2nd Int'l Conf on GA's)
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*
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* src/backend/optimizer/geqo/geqo_cx.c
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*
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*-------------------------------------------------------------------------
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*/
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/* contributed by:
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=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
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* Martin Utesch * Institute of Automatic Control *
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= = University of Mining and Technology =
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* utesch@aut.tu-freiberg.de * Freiberg, Germany *
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=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
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*/
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/* the cx algorithm is adopted from Genitor : */
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/*************************************************************/
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/* */
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/* Copyright (c) 1990 */
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/* Darrell L. Whitley */
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/* Computer Science Department */
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/* Colorado State University */
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/* */
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/* Permission is hereby granted to copy all or any part of */
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/* this program for free distribution. The author's name */
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/* and this copyright notice must be included in any copy. */
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/* */
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/*************************************************************/
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#include "postgres.h"
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#include "optimizer/geqo_random.h"
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#include "optimizer/geqo_recombination.h"
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#if defined(CX)
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/* cx
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*
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* cycle crossover
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*/
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int
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cx(PlannerInfo *root, Gene *tour1, Gene *tour2, Gene *offspring,
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int num_gene, City * city_table)
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{
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int i,
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start_pos,
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curr_pos;
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int count = 0;
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int num_diffs = 0;
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/* initialize city table */
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for (i = 1; i <= num_gene; i++)
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{
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city_table[i].used = 0;
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city_table[tour2[i - 1]].tour2_position = i - 1;
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city_table[tour1[i - 1]].tour1_position = i - 1;
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}
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/* choose random cycle starting position */
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start_pos = geqo_randint(root, num_gene - 1, 0);
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/* child inherits first city */
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offspring[start_pos] = tour1[start_pos];
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/* begin cycle with tour1 */
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curr_pos = start_pos;
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city_table[(int) tour1[start_pos]].used = 1;
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count++;
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/* cx main part */
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/* STEP 1 */
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while (tour2[curr_pos] != tour1[start_pos])
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{
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city_table[(int) tour2[curr_pos]].used = 1;
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curr_pos = city_table[(int) tour2[curr_pos]].tour1_position;
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offspring[curr_pos] = tour1[curr_pos];
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count++;
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}
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/* STEP 2 */
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/* failed to create a complete tour */
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if (count < num_gene)
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{
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for (i = 1; i <= num_gene; i++)
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{
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if (!city_table[i].used)
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{
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offspring[city_table[i].tour2_position] =
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tour2[(int) city_table[i].tour2_position];
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count++;
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}
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}
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}
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/* STEP 3 */
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/* still failed to create a complete tour */
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if (count < num_gene)
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{
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/* count the number of differences between mom and offspring */
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for (i = 0; i < num_gene; i++)
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if (tour1[i] != offspring[i])
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num_diffs++;
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}
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return num_diffs;
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}
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#endif /* defined(CX) */
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