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/*------------------------------------------------------------------------
*
* geqo_px.c
*
* position crossover [PX] routines;
* PX operator according to Syswerda
* (The Genetic Algorithms Handbook, L Davis, ed)
*
* $Id: geqo_px.c,v 1.9 1999/07/16 04:59:12 momjian Exp $
*
*-------------------------------------------------------------------------
*/
/* contributed by:
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
* Martin Utesch * Institute of Automatic Control *
= = University of Mining and Technology =
* utesch@aut.tu-freiberg.de * Freiberg, Germany *
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
*/
/* the px 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"
/* px
*
* position crossover
*/
void
px(Gene *tour1, Gene *tour2, Gene *offspring, int num_gene, City *city_table)
{
int num_positions;
int i,
pos,
tour2_index,
offspring_index;
/* initialize city table */
for (i = 1; i <= num_gene; i++)
city_table[i].used = 0;
/* choose random positions that will be inherited directly from parent */
num_positions = geqo_randint(2 * num_gene / 3, num_gene / 3);
/* choose random position */
for (i = 0; i < num_positions; i++)
{
pos = geqo_randint(num_gene - 1, 0);
offspring[pos] = tour1[pos]; /* transfer cities to child */
city_table[(int) tour1[pos]].used = 1; /* mark city used */
}
tour2_index = 0;
offspring_index = 0;
/* px main part */
while (offspring_index < num_gene)
{
/* next position in offspring filled */
if (!city_table[(int) tour1[offspring_index]].used)
{
/* next city in tour1 not used */
if (!city_table[(int) tour2[tour2_index]].used)
{
/* inherit from tour1 */
offspring[offspring_index] = tour2[tour2_index];
tour2_index++;
offspring_index++;
}
else
{ /* next city in tour2 has been used */
tour2_index++;
}
}
else
{ /* next position in offspring is filled */
offspring_index++;
}
}
}
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