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/*
* libpinyin
* Library to deal with pinyin.
*
* Copyright (C) 2011 Peng Wu <alexepico@gmail.com>
*
* This program 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 2 of the License, or
* (at your option) any later version.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <errno.h>
#include <locale.h>
#include "pinyin_internal.h"
#include "k_mixture_model.h"
static guint32 g_prune_k = 3;
static parameter_t g_prune_poss = 0.99;
void print_help(){
printf("Usage: prune_k_mixture_model -k <INT> --CDF <FLOAT> <FILENAME>\n");
}
bool prune_k_mixture_model(KMixtureModelMagicHeader * magic_header,
KMixtureModelSingleGram * & bigram,
FlexibleBigramPhraseArray removed_array){
bool success;
FlexibleBigramPhraseArray array = g_array_new(FALSE, FALSE, sizeof(KMixtureModelArrayItemWithToken));
bigram->retrieve_all(array);
for ( size_t i = 0; i < array->len; ++i) {
KMixtureModelArrayItemWithToken * item = &g_array_index(array, KMixtureModelArrayItemWithToken, i);
phrase_token_t token = item->m_token;
parameter_t remained_poss = 1; parameter_t one_poss = 0;
bool errors = false;
for ( size_t k = 0; k < g_prune_k; ++k){
one_poss = compute_Pr_G_3_with_count
(k, magic_header->m_N, item->m_item.m_WC,
magic_header->m_N - item->m_item.m_N_n_0,
item->m_item.m_n_1);
if ( !(0 <= one_poss && one_poss <= 1) )
errors = true;
remained_poss -= one_poss;
}
if ( fabs(remained_poss) < DBL_EPSILON )
remained_poss = 0.;
/* some wrong possibility. */
if ( errors || !(0 <= remained_poss && remained_poss <= 1) ) {
fprintf(stderr, "some wrong possibility is encountered:%f.\n",
remained_poss);
fprintf(stderr, "k:%d N:%d WC:%d n_0:%d n_1:%d\n",
g_prune_k, magic_header->m_N, item->m_item.m_WC,
magic_header->m_N - item->m_item.m_N_n_0,
item->m_item.m_n_1);
exit(EDOM);
}
if ( remained_poss < g_prune_poss ) {
/* prune this word or phrase. */
KMixtureModelArrayItem removed_item;
bigram->remove_array_item(token, removed_item);
assert( memcmp(&removed_item, &(item->m_item),
sizeof(KMixtureModelArrayItem)) == 0 );
KMixtureModelArrayItemWithToken removed_item_with_token;
removed_item_with_token.m_token = token;
removed_item_with_token.m_item = removed_item;
g_array_append_val(removed_array, removed_item_with_token);
KMixtureModelArrayHeader array_header;
bigram->get_array_header(array_header);
guint32 removed_count = removed_item.m_WC;
array_header.m_WC -= removed_count;
bigram->set_array_header(array_header);
magic_header->m_WC -= removed_count;
magic_header->m_total_freq -= removed_count;
}
}
return true;
}
int main(int argc, char * argv[]){
int i = 1;
const char * bigram_filename = NULL;
setlocale(LC_ALL, "");
while ( i < argc ){
if ( strcmp("--help", argv[i]) == 0 ){
print_help();
exit(0);
} else if ( strcmp("-k", argv[i]) == 0 ){
if ( ++i >= argc ){
print_help();
exit(EINVAL);
}
g_prune_k = atoi(argv[i]);
} else if ( strcmp("--CDF", argv[i]) == 0 ){
if ( ++i >= argc ){
print_help();
exit(EINVAL);
}
g_prune_poss = atof(argv[i]);
} else {
bigram_filename = argv[i];
}
++i;
}
/* TODO: magic header signature check here. */
KMixtureModelBigram bigram(K_MIXTURE_MODEL_MAGIC_NUMBER);
bigram.attach(bigram_filename, ATTACH_READWRITE);
KMixtureModelMagicHeader magic_header;
bigram.get_magic_header(magic_header);
GArray * items = g_array_new(FALSE, FALSE, sizeof(phrase_token_t));
bigram.get_all_items(items);
/* print prune progress */
size_t progress = 0; size_t onestep = items->len / 20;
for ( size_t i = 0; i < items->len; ++i ){
if ( progress >= onestep ) {
progress = 0; fprintf(stderr, "*");
}
progress ++;
phrase_token_t * token = &g_array_index(items, phrase_token_t, i);
KMixtureModelSingleGram * single_gram = NULL;
bigram.load(*token, single_gram);
FlexibleBigramPhraseArray removed_array = g_array_new(FALSE, FALSE, sizeof(KMixtureModelArrayItemWithToken));
prune_k_mixture_model(&magic_header, single_gram, removed_array);
bigram.store(*token, single_gram);
delete single_gram;
/* post processing for unigram reduce */
for (size_t m = 0; m < removed_array->len; ++m ){
KMixtureModelArrayItemWithToken * item =
&g_array_index(removed_array,
KMixtureModelArrayItemWithToken, m);
KMixtureModelArrayHeader array_header;
assert(bigram.get_array_header(item->m_token, array_header));
array_header.m_freq -= item->m_item.m_WC;
assert(array_header.m_freq >= 0);
assert(bigram.set_array_header(item->m_token, array_header));
}
g_array_free(removed_array, TRUE);
removed_array = NULL;
}
fprintf(stderr, "\n");
bigram.set_magic_header(magic_header);
/* post processing clean up zero items */
KMixtureModelArrayHeader array_header;
for ( size_t i = 0; i < items->len; ++i ){
phrase_token_t * token = &g_array_index(items, phrase_token_t, i);
assert(bigram.get_array_header(*token, array_header));
if ( 0 == array_header.m_WC && 0 == array_header.m_freq )
assert(bigram.remove(*token));
}
g_array_free(items, TRUE);
return 0;
}
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