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/*
* libpinyin
* Library to deal with pinyin.
*
* Copyright (C) 2006-2008 Peng Wu
*
* 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <locale.h>
#include <math.h>
#include <glib.h>
#include "pinyin_internal.h"
parameter_t compute_interpolation(SingleGram * deleted_bigram,
FacadePhraseIndex * unigram,
SingleGram * bigram){
bool success;
parameter_t lambda = 0, next_lambda = 0.6;
parameter_t epsilon = 0.001;
while ( fabs(lambda - next_lambda) > epsilon){
lambda = next_lambda;
next_lambda = 0;
guint32 table_num = 0;
parameter_t numerator = 0;
parameter_t part_of_denominator = 0;
BigramPhraseWithCountArray array = g_array_new(FALSE, FALSE, sizeof(BigramPhraseItemWithCount));
deleted_bigram->retrieve_all(array);
for ( int i = 0; i < array->len; ++i){
BigramPhraseItemWithCount * item = &g_array_index(array, BigramPhraseItemWithCount, i);
//get the phrase token
phrase_token_t token = item->m_token;
guint32 deleted_count = item->m_count;
{
guint32 freq = 0;
parameter_t elem_poss = 0;
if (bigram && bigram->get_freq(token, freq)){
guint32 total_freq;
assert(bigram->get_total_freq(total_freq));
assert(0 != total_freq);
elem_poss = freq / (parameter_t) total_freq;
}
numerator = lambda * elem_poss;
}
{
guint32 freq = 0;
parameter_t elem_poss = 0;
PhraseItem item;
if (!unigram->get_phrase_item(token, item)){
guint32 freq = item.get_unigram_frequency();
guint32 total_freq = unigram->get_phrase_index_total_freq();
elem_poss = freq / (parameter_t)total_freq;
}
part_of_denominator = (1 - lambda) * elem_poss;
}
if (0 == (numerator + part_of_denominator))
continue;
next_lambda += deleted_count * (numerator / (numerator + part_of_denominator));
}
assert(deleted_bigram->get_total_freq(table_num));
next_lambda /= table_num;
g_array_free(array, TRUE);
}
lambda = next_lambda;
return lambda;
}
int main(int argc, char * argv[]){
FacadePhraseIndex phrase_index;
//gb_char binary file
MemoryChunk * chunk = new MemoryChunk;
chunk->load("gb_char.bin");
phrase_index.load(1, chunk);
//gbk_char binary file
chunk = new MemoryChunk;
chunk->load("gbk_char.bin");
phrase_index.load(2, chunk);
Bigram bigram;
bigram.attach("bigram.db", ATTACH_READONLY);
Bigram deleted_bigram;
deleted_bigram.attach("deleted_bigram.db", ATTACH_READONLY);
GArray * deleted_items = g_array_new(FALSE, FALSE, sizeof(phrase_token_t));
deleted_bigram.get_all_items(deleted_items);
parameter_t lambda_sum = 0;
int lambda_count = 0;
for ( int i = 0; i < deleted_items->len; ++i ){
phrase_token_t * token = &g_array_index(deleted_items, phrase_token_t, i);
SingleGram * single_gram = NULL;
bigram.load(*token, single_gram);
SingleGram * deleted_single_gram = NULL;
deleted_bigram.load(*token, deleted_single_gram);
parameter_t lambda = compute_interpolation(deleted_single_gram, &phrase_index, single_gram);
printf("token:%d lambda:%f\n", *token, lambda);
lambda_sum += lambda;
lambda_count ++;
if (single_gram)
delete single_gram;
delete deleted_single_gram;
}
printf("average lambda:%f\n", (lambda_sum/lambda_count));
g_array_free(deleted_items, TRUE);
return 0;
}
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