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/*------------------------------------------------------------------------
*
* geqo_pool.c
* Genetic Algorithm (GA) pool stuff
*
* Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: geqo_pool.c,v 1.21 2003/08/04 02:39:59 momjian Exp $
*
*-------------------------------------------------------------------------
*/
/* contributed by:
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
* Martin Utesch * Institute of Automatic Control *
= = University of Mining and Technology =
* utesch@aut.tu-freiberg.de * Freiberg, Germany *
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
*/
/* -- parts of this are adapted from D. Whitley's Genitor algorithm -- */
#include "postgres.h"
#include "optimizer/geqo.h"
#include "optimizer/geqo_copy.h"
#include "optimizer/geqo_pool.h"
#include "optimizer/geqo_recombination.h"
static int compare(const void *arg1, const void *arg2);
/*
* alloc_pool
* allocates memory for GA pool
*/
Pool *
alloc_pool(int pool_size, int string_length)
{
Pool *new_pool;
Chromosome *chromo;
int i;
/* pool */
new_pool = (Pool *) palloc(sizeof(Pool));
new_pool->size = (int) pool_size;
new_pool->string_length = (int) string_length;
/* all chromosome */
new_pool->data = (Chromosome *) palloc(pool_size * sizeof(Chromosome));
/* all gene */
chromo = (Chromosome *) new_pool->data; /* vector of all chromos */
for (i = 0; i < pool_size; i++)
chromo[i].string = palloc((string_length + 1) * sizeof(Gene));
return new_pool;
}
/*
* free_pool
* deallocates memory for GA pool
*/
void
free_pool(Pool *pool)
{
Chromosome *chromo;
int i;
/* all gene */
chromo = (Chromosome *) pool->data; /* vector of all chromos */
for (i = 0; i < pool->size; i++)
pfree(chromo[i].string);
/* all chromosome */
pfree(pool->data);
/* pool */
pfree(pool);
}
/*
* random_init_pool
* initialize genetic pool
*/
void
random_init_pool(Query *root, List *initial_rels,
Pool *pool, int strt, int stp)
{
Chromosome *chromo = (Chromosome *) pool->data;
int i;
for (i = strt; i < stp; i++)
{
init_tour(chromo[i].string, pool->string_length);
pool->data[i].worth = geqo_eval(root, initial_rels,
chromo[i].string,
pool->string_length);
}
}
/*
* sort_pool
* sorts input pool according to worth, from smallest to largest
*
* maybe you have to change compare() for different ordering ...
*/
void
sort_pool(Pool *pool)
{
qsort(pool->data, pool->size, sizeof(Chromosome), compare);
}
/*
* compare
* static input function for pg_sort
*
* return values for sort from smallest to largest are prooved!
* don't change them!
*/
static int
compare(const void *arg1, const void *arg2)
{
Chromosome chromo1 = *(Chromosome *) arg1;
Chromosome chromo2 = *(Chromosome *) arg2;
if (chromo1.worth == chromo2.worth)
return 0;
else if (chromo1.worth > chromo2.worth)
return 1;
else
return -1;
}
/* alloc_chromo
* allocates a chromosome and string space
*/
Chromosome *
alloc_chromo(int string_length)
{
Chromosome *chromo;
chromo = (Chromosome *) palloc(sizeof(Chromosome));
chromo->string = (Gene *) palloc((string_length + 1) * sizeof(Gene));
return chromo;
}
/* free_chromo
* deallocates a chromosome and string space
*/
void
free_chromo(Chromosome *chromo)
{
pfree(chromo->string);
pfree(chromo);
}
/* spread_chromo
* inserts a new chromosome into the pool, displacing worst gene in pool
* assumes best->worst = smallest->largest
*/
void
spread_chromo(Chromosome *chromo, Pool *pool)
{
int top,
mid,
bot;
int i,
index;
Chromosome swap_chromo,
tmp_chromo;
/* new chromo is so bad we can't use it */
if (chromo->worth > pool->data[pool->size - 1].worth)
return;
/* do a binary search to find the index of the new chromo */
top = 0;
mid = pool->size / 2;
bot = pool->size - 1;
index = -1;
while (index == -1)
{
/* these 4 cases find a new location */
if (chromo->worth <= pool->data[top].worth)
index = top;
else if (chromo->worth == pool->data[mid].worth)
index = mid;
else if (chromo->worth == pool->data[bot].worth)
index = bot;
else if (bot - top <= 1)
index = bot;
/*
* these 2 cases move the search indices since a new location has
* not yet been found.
*/
else if (chromo->worth < pool->data[mid].worth)
{
bot = mid;
mid = top + ((bot - top) / 2);
}
else
{ /* (chromo->worth > pool->data[mid].worth) */
top = mid;
mid = top + ((bot - top) / 2);
}
} /* ... while */
/* now we have index for chromo */
/*
* move every gene from index on down one position to make room for
* chromo
*/
/*
* copy new gene into pool storage; always replace worst gene in pool
*/
geqo_copy(&pool->data[pool->size - 1], chromo, pool->string_length);
swap_chromo.string = pool->data[pool->size - 1].string;
swap_chromo.worth = pool->data[pool->size - 1].worth;
for (i = index; i < pool->size; i++)
{
tmp_chromo.string = pool->data[i].string;
tmp_chromo.worth = pool->data[i].worth;
pool->data[i].string = swap_chromo.string;
pool->data[i].worth = swap_chromo.worth;
swap_chromo.string = tmp_chromo.string;
swap_chromo.worth = tmp_chromo.worth;
}
}
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