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/*------------------------------------------------------------------------
*
* geqo_ox2.c
*
* order crossover [OX] routines;
* OX2 operator according to Syswerda
* (The Genetic Algorithms Handbook, ed L Davis)
*
* src/backend/optimizer/geqo/geqo_ox2.c
*
*-------------------------------------------------------------------------
*/
/* contributed by:
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
* Martin Utesch * Institute of Automatic Control *
= = University of Mining and Technology =
* utesch@aut.tu-freiberg.de * Freiberg, Germany *
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
*/
/* the ox algorithm is adopted from Genitor : */
/*************************************************************/
/* */
/* Copyright (c) 1990 */
/* Darrell L. Whitley */
/* Computer Science Department */
/* Colorado State University */
/* */
/* Permission is hereby granted to copy all or any part of */
/* this program for free distribution. The author's name */
/* and this copyright notice must be included in any copy. */
/* */
/*************************************************************/
#include "postgres.h"
#include "optimizer/geqo_random.h"
#include "optimizer/geqo_recombination.h"
#if defined(OX2)
/* ox2
*
* position crossover
*/
void
ox2(PlannerInfo *root, Gene *tour1, Gene *tour2, Gene *offspring, int num_gene, City * city_table)
{
int k,
j,
count,
pos,
select,
num_positions;
/* initialize city table */
for (k = 1; k <= num_gene; k++)
{
city_table[k].used = 0;
city_table[k - 1].select_list = -1;
}
/* determine the number of positions to be inherited from tour1 */
num_positions = geqo_randint(root, 2 * num_gene / 3, num_gene / 3);
/* make a list of selected cities */
for (k = 0; k < num_positions; k++)
{
pos = geqo_randint(root, num_gene - 1, 0);
city_table[pos].select_list = (int) tour1[pos];
city_table[(int) tour1[pos]].used = 1; /* mark used */
}
count = 0;
k = 0;
/* consolidate the select list to adjacent positions */
while (count < num_positions)
{
if (city_table[k].select_list == -1)
{
j = k + 1;
while ((city_table[j].select_list == -1) && (j < num_gene))
j++;
city_table[k].select_list = city_table[j].select_list;
city_table[j].select_list = -1;
count++;
}
else
count++;
k++;
}
select = 0;
for (k = 0; k < num_gene; k++)
{
if (city_table[(int) tour2[k]].used)
{
offspring[k] = (Gene) city_table[select].select_list;
select++; /* next city in the select list */
}
else
/* city isn't used yet, so inherit from tour2 */
offspring[k] = tour2[k];
}
}
#endif /* defined(OX2) */
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