[위 에]word2vec 소스 코드 분석 word2vec.c

//     word2vec.c   
//          ，        http://www.cnblogs.com/downtjs/p/3784440.html


//  Copyright 2013 Google Inc. All Rights Reserved.
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <pthread.h>

#define MAX_STRING 100
#define EXP_TABLE_SIZE 1000
#define MAX_EXP 6
#define MAX_SENTENCE_LENGTH 1000
#define MAX_CODE_LENGTH 40

const int vocab_hash_size = 30000000;  // Maximum 30 * 0.7 = 21M words in the vocabulary

typedef float real;                    // Precision of float numbers

struct vocab_word
{
  long long cn;//  
  int *point;//huffman          
  char *word, *code, codelen;//huffman  
};

char train_file[MAX_STRING], output_file[MAX_STRING];
char save_vocab_file[MAX_STRING], read_vocab_file[MAX_STRING];
struct vocab_word *vocab;
int binary = 0, cbow = 0, debug_mode = 2, window = 5, min_count = 5, num_threads = 1, min_reduce = 1;
int *vocab_hash;
long long vocab_max_size = 1000, vocab_size = 0, layer1_size = 100;
long long train_words = 0, word_count_actual = 0, file_size = 0, classes = 0;
real alpha = 0.025, starting_alpha, sample = 0;
real *syn0, *syn1, *syn1neg, *expTable;
clock_t start;

int hs = 1, negative = 0;
const int table_size = 1e8;
int *table;


//          ，table         
void InitUnigramTable()
{
  int a, i;
  long long train_words_pow = 0;
  real d1, power = 0.75;
  table = (int *)malloc(table_size * sizeof(int));
  for (a = 0; a < vocab_size; a++) //     ，        train_words_pow，  power        。
	  train_words_pow += pow(vocab[a].cn, power);
  i = 0;
  d1 = pow(vocab[i].cn, power) / (real)train_words_pow;//                   
  for (a = 0; a < table_size; a++)//  table。a  table   ，i        
  {
    table[a] = i;//  i  table a  
    //table             ，        ，    table     
    if (a / (real)table_size > d1)
    {
      i++;//       
      d1 += pow(vocab[i].cn, power) / (real)train_words_pow;
    }
    if (i >= vocab_siInitNetze) i = vocab_size - 1;
  }
}

// Reads a single word from a file, assuming space + tab + EOL to be word boundaries
//         
void ReadWord(char *word, FILE *fin) {
  int a = 0, ch;
  while (!feof(fin)) {
    ch = fgetc(fin);
    if (ch == 13) continue;
    if ((ch == ' ') || (ch == '\t') || (ch == '
')) {
      if (a > 0) {
        if (ch == '
') ungetc(ch, fin);
        break;
      }
      if (ch == '
') {
        strcpy(word, (char *)"</s>");
        return;
      } else continue;
    }
    word[a] = ch;
    a++;
    if (a >= MAX_STRING - 1) a--;   // Truncate too long words
  }
  word[a] = 0;
}

// Returns hash value of a word      hash ，    hash     （    ）
int GetWordHash(char *word)
{
  unsigned long long a, hash = 0;
  for (a = 0; a < strlen(word); a++)
	  hash = hash * 257 + word[a];//  257  
  hash = hash % vocab_hash_size;
  return hash;
}

// Returns position of a word in the vocabulary; if the word is not found, returns -1
//              ，        -1
int SearchVocab(char *word)
{
  unsigned int hash = GetWordHash(word);
  while (1)
  {
    if (vocab_hash[hash] == -1) return -1;
    if (!strcmp(word, vocab[vocab_hash[hash]].word))
    	return vocab_hash[hash];
    hash = (hash + 1) % vocab_hash_size;
  }
  return -1;
}

// Reads a word and returns its index in the vocabulary
//           ，              
int ReadWordIndex(FILE *fin)
{
  char word[MAX_STRING];
  ReadWord(word, fin);
  if (feof(fin)) return -1;
  return SearchVocab(word);
}

// Adds a word to the vocabulary             
int AddWordToVocab(char *word)
{
  unsigned int hash, length = strlen(word) + 1;
  if (length > MAX_STRING)
	  length = MAX_STRING;
  vocab[vocab_size].word = (char *)calloc(length, sizeof(char));
  strcpy(vocab[vocab_size].word, word);
  vocab[vocab_size].cn = 0;
  vocab_size++;
  // Reallocate memory if needed
  if (vocab_size + 2 >= vocab_max_size)
  {
    vocab_max_size += 1000;
    vocab = (struct vocab_word *)realloc(vocab, vocab_max_size * sizeof(struct vocab_word));
  }
  hash = GetWordHash(word);
  while (vocab_hash[hash] != -1)//  hash    
	  hash = (hash + 1) % vocab_hash_size;//           
  vocab_hash[hash] = vocab_size - 1;//   hash              
  return vocab_size - 1;
}

// Used later for sorting by word counts
int VocabCompare(const void *a, const void *b)
{
    return ((struct vocab_word *)b)->cn - ((struct vocab_word *)a)->cn;
}

// Sorts the vocabulary by frequency using word counts
//       
void SortVocab()
{
  int a, size;
  unsigned int hash;
  // Sort the vocabulary and keep </s> at the first position
  qsort(&vocab[1], vocab_size - 1, sizeof(struct vocab_word), VocabCompare);
  for (a = 0; a < vocab_hash_size; a++)
	  vocab_hash[a] = -1;
  size = vocab_size;
  train_words = 0;
  for (a = 0; a < size; a++)
  {
    // Words occuring less than min_count times will be discarded from the vocab
	//          
    if (vocab[a].cn < min_count)
    {
      vocab_size--;
      free(vocab[vocab_size].word);
    }
    else
    {
      // Hash will be re-computed, as after the sorting it is not actual
      //     hash  。vocab_hash  hash         
      hash=GetWordHash(vocab[a].word);
      while (vocab_hash[hash] != -1) hash = (hash + 1) % vocab_hash_size;
      vocab_hash[hash] = a;
      train_words += vocab[a].cn;
    }
  }
  vocab = (struct vocab_word *)realloc(vocab, (vocab_size + 1) * sizeof(struct vocab_word));
  // Allocate memory for the binary tree construction
  for (a = 0; a < vocab_size; a++)
  {
    vocab[a].code = (char *)calloc(MAX_CODE_LENGTH, sizeof(char));
    vocab[a].point = (int *)calloc(MAX_CODE_LENGTH, sizeof(int));
  }
}

// Reduces the vocabulary by removing infrequent tokens
//           ，     
void ReduceVocab()
{
  int a, b = 0;
  unsigned int hash;
  for (a = 0; a < vocab_size; a++)//  ，       
  if (vocab[a].cn > min_reduce)
  {
    vocab[b].cn = vocab[a].cn;
    vocab[b].word = vocab[a].word;
    b++;
  }
  else free(vocab[a].word);
  vocab_size = b;
  for (a = 0; a < vocab_hash_size; a++) vocab_hash[a] = -1;
  for (a = 0; a < vocab_size; a++) {
    // Hash will be re-computed, as it is not actual
    hash = GetWordHash(vocab[a].word);
    while (vocab_hash[hash] != -1) hash = (hash + 1) % vocab_hash_size;
    vocab_hash[hash] = a;
  }
  fflush(stdout);
  min_reduce++;
}

// Create binary Huffman tree using the word counts      huffman 
// Frequent words will have short uniqe binary codes           huffman  
void CreateBinaryTree() {
  long long a, b, i, min1i, min2i, pos1, pos2, point[MAX_CODE_LENGTH];
  char code[MAX_CODE_LENGTH];
  long long *count = (long long *)calloc(vocab_size * 2 + 1, sizeof(long long));
  long long *binary = (long long *)calloc(vocab_size * 2 + 1, sizeof(long long));
  long long *parent_node = (long long *)calloc(vocab_size * 2 + 1, sizeof(long long));
  for (a = 0; a < vocab_size; a++) count[a] = vocab[a].cn;
  for (a = vocab_size; a < vocab_size * 2; a++) count[a] = 1e15;
  pos1 = vocab_size - 1;
  pos2 = vocab_size;
  // Following algorithm constructs the Huffman tree by adding one node at a time
  for (a = 0; a < vocab_size - 1; a++)
  {
    // First, find two smallest nodes 'min1, min2'              
    if (pos1 >= 0)//          
    {
      if (count[pos1] < count[pos2])
      {
        min1i = pos1;
        pos1--;
      }
      else
      {
        min1i = pos2;
        pos2++;
      }
    }
    else
    {
      min1i = pos2;
      pos2++;
    }
    if (pos1 >= 0)//          
    {
      if (count[pos1] < count[pos2])
      {
        min2i = pos1;
        pos1--;
      }
      else
      {
        min2i = pos2;
        pos2++;
      }
    }
    else
    {
      min2i = pos2;
      pos2++;
    }
    count[vocab_size + a] = count[min1i] + count[min2i];
    parent_node[min1i] = vocab_size + a;
    parent_node[min2i] = vocab_size + a;
    binary[min2i] = 1;//     1，     0。
  }
  // Now assign binary code to each vocabulary word
  for (a = 0; a < vocab_size; a++)
  {
    b = a;
    i = 0;
    while (1)
    {
      code[i] = binary[b];
      point[i] = b;
      i++;
      b = parent_node[b];
      if (b == vocab_size * 2 - 2) break;
    }
    vocab[a].codelen = i;
    vocab[a].point[0] = vocab_size - 2;
    for (b = 0; b < i; b++)
    {
      vocab[a].code[i - b - 1] = code[b];
      vocab[a].point[i - b] = point[b] - vocab_size;
    }
  }
  free(count);
  free(binary);
  free(parent_node);
}

//               
void LearnVocabFromTrainFile()
{
  char word[MAX_STRING];
  FILE *fin;
  long long a, i;
  for (a = 0; a < vocab_hash_size; a++) vocab_hash[a] = -1;
  fin = fopen(train_file, "rb");
  if (fin == NULL)
  {
    printf("ERROR: training data file not found!
");
    exit(1);
  }
  vocab_size = 0;
  AddWordToVocab((char *)"</s>");
  while (1)
  {
    ReadWord(word, fin);
    if (feof(fin)) break;
    train_words++;
    if ((debug_mode > 1) && (train_words % 100000 == 0))
    {
      printf("%lldK%c", train_words / 1000, 13);
      fflush(stdout);
    }
    i = SearchVocab(word);//            
    if (i == -1)//       
    {
      a = AddWordToVocab(word);//          
      vocab[a].cn = 1;
    }
    else vocab[i].cn++;//    
    if (vocab_size > vocab_hash_size * 0.7)//        ，   
    	ReduceVocab();
  }
  SortVocab();//         
  if (debug_mode > 0)
  {
    printf("Vocab size: %lld
", vocab_size);
    printf("Words in train file: %lld
", train_words);
  }
  file_size = ftell(fin);
  fclose(fin);
}

void SaveVocab() {
  long long i;
  FILE *fo = fopen(save_vocab_file, "wb");
  for (i = 0; i < vocab_size; i++) fprintf(fo, "%s %lld
", vocab[i].word, vocab[i].cn);
  fclose(fo);
}

//       ，                
void ReadVocab()
{
  long long a, i = 0;
  char c;
  char word[MAX_STRING];
  FILE *fin = fopen(read_vocab_file, "rb");//      
  if (fin == NULL)
  {
    printf("Vocabulary file not found
");
    exit(1);
  }
  for (a = 0; a < vocab_hash_size; a++)
	  vocab_hash[a] = -1;
  vocab_size = 0;
  while (1)
  {
    ReadWord(word, fin);// fin      word 
    if (feof(fin)) break;
    a = AddWordToVocab(word);//         ，        
    fscanf(fin, "%lld%c", &vocab[a].cn, &c);//    ？c     ，     
    i++;
  }
  SortVocab();//      
  if (debug_mode > 0)
  {
    printf("Vocab size: %lld
", vocab_size);
    printf("Words in train file: %lld
", train_words);
  }

  //      
  fin = fopen(train_file, "rb");
  if (fin == NULL)
  {
    printf("ERROR: training data file not found!
");
    exit(1);
  }
  fseek(fin, 0, SEEK_END);
  file_size = ftell(fin);
  fclose(fin);
}

void InitNet()
{
  long long a, b;
  a = posix_memalign((void **)&syn0, 128, (long long)vocab_size * layer1_size * sizeof(real));
  //             ，    128         
  if (syn0 == NULL)
  {
	  printf("Memory allocation failed
"); exit(1);
  }
  if (hs)//  softmax
  {
    a = posix_memalign((void **)&syn1, 128, (long long)vocab_size * layer1_size * sizeof(real));
    if (syn1 == NULL)
    {
    	printf("Memory allocation failed
"); exit(1);
    }
    for (b = 0; b < layer1_size; b++)
    	for (a = 0; a < vocab_size; a++)
    		syn1[a * layer1_size + b] = 0;
  }
  if (negative>0)//     
  {
    a = posix_memalign((void **)&syn1neg, 128, (long long)vocab_size * layer1_size * sizeof(real));
    if (syn1neg == NULL)
    {
    	printf("Memory allocation failed
"); exit(1);
    }
    for (b = 0; b < layer1_size; b++)
    	for (a = 0; a < vocab_size; a++)
    		syn1neg[a * layer1_size + b] = 0;
  }
  for (b = 0; b < layer1_size; b++)
	  for (a = 0; a < vocab_size; a++)
		  syn0[a * layer1_size + b] = (rand() / (real)RAND_MAX - 0.5) / layer1_size;
  CreateBinaryTree();//  huffman ，         
}


//          ，         ：          ，     huffman  
void *TrainModelThread(void *id)
{
  long long a, b, d, word, last_word, sentence_length = 0, sentence_position = 0;
  long long word_count = 0, last_word_count = 0, sen[MAX_SENTENCE_LENGTH + 1];
  long long l1, l2, c, target, label;
  unsigned long long next_random = (long long)id;
  real f, g;
  clock_t now;
  real *neu1 = (real *)calloc(layer1_size, sizeof(real));
  real *neu1e = (real *)calloc(layer1_size, sizeof(real));
  FILE *fi = fopen(train_file, "rb");
  //          。    id              
  fseek(fi, file_size / (long long)num_threads * (long long)id, SEEK_SET);
  while (1)
  {
    if (word_count - last_word_count > 10000)
    {
      word_count_actual += word_count - last_word_count;
      last_word_count = word_count;
      if ((debug_mode > 1))
      {
        now=clock();
        printf("%cAlpha: %f  Progress: %.2f%%  Words/thread/sec: %.2fk  ", 13, alpha,
         word_count_actual / (real)(train_words + 1) * 100,
         word_count_actual / ((real)(now - start + 1) / (real)CLOCKS_PER_SEC * 1000));
        fflush(stdout);
      }
      alpha = starting_alpha * (1 - word_count_actual / (real)(train_words + 1));
      if (alpha < starting_alpha * 0.0001) alpha = starting_alpha * 0.0001;
    }
    if (sentence_length == 0)
    {
      while (1)
      {
        word = ReadWordIndex(fi);//          ，              
        if (feof(fi)) break;
        if (word == -1) continue;
        word_count++;
        if (word == 0) break;
        // The subsampling randomly discards frequent words while keeping the ranking same
        if (sample > 0)//         ，         。
        {
          real ran = (sqrt(vocab[word].cn / (sample * train_words)) + 1) * (sample * train_words) / vocab[word].cn;
          next_random = next_random * (unsigned long long)25214903917 + 11;
          if (ran < (next_random & 0xFFFF) / (real)65536) continue;
        }
        sen[sentence_length] = word;
        sentence_length++;
        //1000         ？
        if (sentence_length >= MAX_SENTENCE_LENGTH) break;
      }
      sentence_position = 0;
    }
    if (feof(fi)) break;
    if (word_count > train_words / num_threads) break;//                  ，   。
    word = sen[sentence_position];
    if (word == -1) continue;
    for (c = 0; c < layer1_size; c++) neu1[c] = 0;
    for (c = 0; c < layer1_size; c++) neu1e[c] = 0;
    next_random = next_random * (unsigned long long)25214903917 + 11;
    b = next_random % window;
    if (cbow)
    {  //train the cbow architecture
      // in -> hidden
      for (a = b; a < window * 2 + 1 - b; a++) if (a != window)//             
      {
        c = sentence_position - window + a;
        if (c < 0) continue;
        if (c >= sentence_length) continue;
        last_word = sen[c];
        if (last_word == -1) continue;
        for (c = 0; c < layer1_size; c++)//layer1_size      ，    100
        	neu1[c] += syn0[c + last_word * layer1_size];//       ？
      }
      if (hs) for (d = 0; d < vocab[word].codelen; d++)//    huffman ，      
      {
        f = 0;
        l2 = vocab[word].point[d] * layer1_size;//point      huffman   。      ，     
        // Propagate hidden -> output
        for (c = 0; c < layer1_size; c++) f += neu1[c] * syn1[c + l2];//    
        if (f <= -MAX_EXP) continue;//           
        else if (f >= MAX_EXP) continue;
        else f = expTable[(int)((f + MAX_EXP) * (EXP_TABLE_SIZE / MAX_EXP / 2))];//    sigmoid  
        // 'g' is the gradient multiplied by the learning rate
        g = (1 - vocab[word].code[d] - f) * alpha;//       

        //layer1_size      
        // Propagate errors output -> hidden       ， huffman      。                   ，syn1[c + l2]        。
        for (c = 0; c < layer1_size; c++) neu1e[c] += g * syn1[c + l2];

        // Learn weights hidden -> output           ，   neu1[c]          
        for (c = 0; c < layer1_size; c++) syn1[c + l2] += g * neu1[c];
      }
      // NEGATIVE SAMPLING
      if (negative > 0)
      for (d = 0; d < negative + 1; d++)
      {
        if (d == 0)
        {
          target = word;//    
          label = 1;//   
        }
        else
        {
          next_random = next_random * (unsigned long long)25214903917 + 11;
          target = table[(next_random >> 16) % table_size];
          if (target == 0) target = next_random % (vocab_size - 1) + 1;
          if (target == word) continue;
          label = 0;//   
        }
        l2 = target * layer1_size;
        f = 0;
        for (c = 0; c < layer1_size; c++)
        	f += neu1[c] * syn1neg[c + l2];//  
        if (f > MAX_EXP)
        	g = (label - 1) * alpha;
        else if (f < -MAX_EXP)
        	g = (label - 0) * alpha;
        else g = (label - expTable[(int)((f + MAX_EXP) * (EXP_TABLE_SIZE / MAX_EXP / 2))]) * alpha;
        for (c = 0; c < layer1_size; c++)
        	neu1e[c] += g * syn1neg[c + l2];//      
        for (c = 0; c < layer1_size; c++)
        	syn1neg[c + l2] += g * neu1[c];//       
      }
      // hidden -> in
      for (a = b; a < window * 2 + 1 - b; a++)
      if (a != window)//cbow               ，           。
      {
        c = sentence_position - window + a;
        if (c < 0) continue;
        if (c >= sentence_length) continue;
        last_word = sen[c];
        if (last_word == -1) continue;
        for (c = 0; c < layer1_size; c++)
        	syn0[c + last_word * layer1_size] += neu1e[c];//     
      }
    }
    else
    {  //train skip-gram
       for (a = b; a < window * 2 + 1 - b; a++)
       if (a != window)//        
       {
        c = sentence_position - window + a;
        if (c < 0) continue;
        if (c >= sentence_length) continue;
        last_word = sen[c];
        if (last_word == -1) continue;
        l1 = last_word * layer1_size;
        for (c = 0; c < layer1_size; c++)
        	neu1e[c] = 0;
        // HIERARCHICAL SOFTMAX
        if (hs)
        for (d = 0; d < vocab[word].codelen; d++)//      
        {
          f = 0;
          l2 = vocab[word].point[d] * layer1_size;//point    huffman   
          // Propagate hidden -> output                 ，           ，     。
          for (c = 0; c < layer1_size; c++)
        	  f += syn0[c + l1] * syn1[c + l2];//          
          if (f <= -MAX_EXP) continue;
          else if (f >= MAX_EXP) continue;
          else f = expTable[(int)((f + MAX_EXP) * (EXP_TABLE_SIZE / MAX_EXP / 2))];
          // 'g' is the gradient multiplied by the learning rate
          g = (1 - vocab[word].code[d] - f) * alpha;//       
          // Propagate errors output -> hidden
          for (c = 0; c < layer1_size; c++)
        	  neu1e[c] += g * syn1[c + l2];//      
          // Learn weights hidden -> output
          for (c = 0; c < layer1_size; c++)
        	  syn1[c + l2] += g * syn0[c + l1];//        
        }
        // NEGATIVE SAMPLING
        if (negative > 0)//   cobow   
        for (d = 0; d < negative + 1; d++)
        {
          if (d == 0)
          {
            target = word;
            label = 1;
          }
          else
          {
            next_random = next_random * (unsigned long long)25214903917 + 11;
            target = table[(next_random >> 16) % table_size];
            if (target == 0) target = next_random % (vocab_size - 1) + 1;
            if (target == word) continue;
            label = 0;
          }
          l2 = target * layer1_size;
          f = 0;
          for (c = 0; c < layer1_size; c++)
        	  f += syn0[c + l1] * syn1neg[c + l2];
          if (f > MAX_EXP) g = (label - 1) * alpha;
          else if (f < -MAX_EXP)
        	  g = (label - 0) * alpha;
          else g = (label - expTable[(int)((f + MAX_EXP) * (EXP_TABLE_SIZE / MAX_EXP / 2))]) * alpha;
          for (c = 0; c < layer1_size; c++)
        	  neu1e[c] += g * syn1neg[c + l2];
          for (c = 0; c < layer1_size; c++)
        	  syn1neg[c + l2] += g * syn0[c + l1];
        }

        // Learn weights input -> hidden
        for (c = 0; c < layer1_size; c++)
        	syn0[c + l1] += neu1e[c];//           
      }
    }
    sentence_position++;
    if (sentence_position >= sentence_length)
    {
      sentence_length = 0;
      continue;
    }
  }
  fclose(fi);
  free(neu1);
  free(neu1e);
  pthread_exit(NULL);
}

void TrainModel()
{
  long a, b, c, d;
  FILE *fo;
  pthread_t *pt = (pthread_t *)malloc(num_threads * sizeof(pthread_t));
  printf("Starting training using file %s
", train_file);
  starting_alpha = alpha;
  if (read_vocab_file[0] != 0)
	  ReadVocab();//       
  else
	  LearnVocabFromTrainFile();//         
  if (save_vocab_file[0] != 0)
	  SaveVocab();//    
  if (output_file[0] == 0)
	  return;
  InitNet();
  if (negative > 0) InitUnigramTable();
  start = clock();
  for (a = 0; a < num_threads; a++) pthread_create(&pt[a], NULL, TrainModelThread, (void *)a);
  for (a = 0; a < num_threads; a++) pthread_join(pt[a], NULL);
  fo = fopen(output_file, "wb");
  if (classes == 0) //     ，        
  {
    // Save the word vectors
    fprintf(fo, "%lld %lld
", vocab_size, layer1_size);
    for (a = 0; a < vocab_size; a++)
    {
      fprintf(fo, "%s ", vocab[a].word);
      if (binary)
    	  for (b = 0; b < layer1_size; b++)
    		  fwrite(&syn0[a * layer1_size + b], sizeof(real), 1, fo);
      else
    	  for (b = 0; b < layer1_size; b++)
    		  fprintf(fo, "%lf ", syn0[a * layer1_size + b]);
      fprintf(fo, "
");
    }
  }
  else //  k-means    
  {
    // Run K-means on the word vectors
    int clcn = classes, iter = 10, closeid;
    int *centcn = (int *)malloc(classes * sizeof(int));//      
    int *cl = (int *)calloc(vocab_size, sizeof(int));//       
    real closev, x;
    real *cent = (real *)calloc(classes * layer1_size, sizeof(real));//    
    for (a = 0; a < vocab_size; a++)
    	cl[a] = a % clcn;//    ？
    for (a = 0; a < iter; a++)
    {
      for (b = 0; b < clcn * layer1_size; b++)
    	  cent[b] = 0;//    
      for (b = 0; b < clcn; b++)
    	  centcn[b] = 1;
      for (c = 0; c < vocab_size; c++)
      {
        for (d = 0; d < layer1_size; d++)
        	cent[layer1_size * cl[c] + d] += syn0[c * layer1_size + d];//         
        centcn[cl[c]]++;//     1
      }
      for (b = 0; b < clcn; b++)//      
      {
        closev = 0;
        for (c = 0; c < layer1_size; c++)
        {
          cent[layer1_size * b + c] /= centcn[b];//  ，       
          closev += cent[layer1_size * b + c] * cent[layer1_size * b + c];
        }
        closev = sqrt(closev);
        for (c = 0; c < layer1_size; c++)
        	cent[layer1_size * b + c] /= closev;//        ？
      }
      for (c = 0; c < vocab_size; c++)//         
      {
        closev = -10;
        closeid = 0;
        for (d = 0; d < clcn; d++)
        {
          x = 0;
          for (b = 0; b < layer1_size; b++)
        	  x += cent[layer1_size * d + b] * syn0[c * layer1_size + b];//  
          if (x > closev)
          {
            closev = x;
            closeid = d;
          }
        }
        cl[c] = closeid;
      }
    }
    // Save the K-means classes
    for (a = 0; a < vocab_size; a++)
    	fprintf(fo, "%s %d
", vocab[a].word, cl[a]);
    free(centcn);
    free(cent);
    free(cl);
  }
  fclose(fo);
}

int ArgPos(char *str, int argc, char **argv)
{
  int a;
  for (a = 1; a < argc; a++) if (!strcmp(str, argv[a]))
  {
    if (a == argc - 1)
    {
      printf("Argument missing for %s
", str);
      exit(1);
    }
    return a;
  }
  return -1;
}

int main(int argc, char **argv) {
  int i;
  if (argc == 1) {
    printf("WORD VECTOR estimation toolkit v 0.1b

");
    printf("Options:
");
    printf("Parameters for training:
");

    //    ：      
    printf("\t-train <file>
");
    printf("\t\tUse text data from <file> to train the model
");

    //    ：        
    printf("\t-output <file>
");
    printf("\t\tUse <file> to save the resulting word vectors / word clusters
");

    //      ，    100
    printf("\t-size <int>
");
    printf("\t\tSet size of word vectors; default is 100
");

    //    ，   5
    printf("\t-window <int>
");
    printf("\t\tSet max skip length between words; default is 5
");

    //          ，              
    printf("\t-sample <float>
");
    printf("\t\tSet threshold for occurrence of words. Those that appear with higher frequency");
    printf(" in the training data will be randomly down-sampled; default is 0 (off), useful value is 1e-5
");

    //    softmax  
    printf("\t-hs <int>
");
    printf("\t\tUse Hierarchical Softmax; default is 1 (0 = not used)
");

    //      ，   0，    5-10。0     。
    printf("\t-negative <int>
");
    printf("\t\tNumber of negative examples; default is 0, common values are 5 - 10 (0 = not used)
");

    //       
    printf("\t-threads <int>
");
    printf("\t\tUse <int> threads (default 1)
");

    //    。            ，     。
    printf("\t-min-count <int>
");
    printf("\t\tThis will discard words that appear less than <int> times; default is 5
");

    //       ，   0.025
    printf("\t-alpha <float>
");
    printf("\t\tSet the starting learning rate; default is 0.025
");

    //     ，      
    printf("\t-classes <int>
");
    printf("\t\tOutput word classes rather than word vectors; default number of classes is 0 (vectors are written)
");

    //debug  ，   2，               
    printf("\t-debug <int>
");
    printf("\t\tSet the debug mode (default = 2 = more info during training)
");

    //   binary      ，   0，   。
    printf("\t-binary <int>
");
    printf("\t\tSave the resulting vectors in binary moded; default is 0 (off)
");

    //         
    printf("\t-save-vocab <file>
");
    printf("\t\tThe vocabulary will be saved to <file>
");

    //        ，          
    printf("\t-read-vocab <file>
");
    printf("\t\tThe vocabulary will be read from <file>, not constructed from the training data
");

    //    continuous bag of words  。   0，        skip-gram   。
    printf("\t-cbow <int>
");
    printf("\t\tUse the continuous bag of words model; default is 0 (skip-gram model)
");

    //      
    printf("
Examples:
");
    printf("./word2vec -train data.txt -output vec.txt -debug 2 -size 200 -window 5 -sample 1e-4 -negative 5 -hs 0 -binary 0 -cbow 1

");
    return 0;
  }
  output_file[0] = 0;
  save_vocab_file[0] = 0;
  read_vocab_file[0] = 0;
  if ((i = ArgPos((char *)"-size", argc, argv)) > 0) layer1_size = atoi(argv[i + 1]);
  if ((i = ArgPos((char *)"-train", argc, argv)) > 0) strcpy(train_file, argv[i + 1]);
  if ((i = ArgPos((char *)"-save-vocab", argc, argv)) > 0) strcpy(save_vocab_file, argv[i + 1]);
  if ((i = ArgPos((char *)"-read-vocab", argc, argv)) > 0) strcpy(read_vocab_file, argv[i + 1]);
  if ((i = ArgPos((char *)"-debug", argc, argv)) > 0) debug_mode = atoi(argv[i + 1]);
  if ((i = ArgPos((char *)"-binary", argc, argv)) > 0) binary = atoi(argv[i + 1]);
  if ((i = ArgPos((char *)"-cbow", argc, argv)) > 0) cbow = atoi(argv[i + 1]);
  if ((i = ArgPos((char *)"-alpha", argc, argv)) > 0) alpha = atof(argv[i + 1]);
  if ((i = ArgPos((char *)"-output", argc, argv)) > 0) strcpy(output_file, argv[i + 1]);
  if ((i = ArgPos((char *)"-window", argc, argv)) > 0) window = atoi(argv[i + 1]);
  if ((i = ArgPos((char *)"-sample", argc, argv)) > 0) sample = atof(argv[i + 1]);
  if ((i = ArgPos((char *)"-hs", argc, argv)) > 0) hs = atoi(argv[i + 1]);
  if ((i = ArgPos((char *)"-negative", argc, argv)) > 0) negative = atoi(argv[i + 1]);
  if ((i = ArgPos((char *)"-threads", argc, argv)) > 0) num_threads = atoi(argv[i + 1]);
  if ((i = ArgPos((char *)"-min-count", argc, argv)) > 0) min_count = atoi(argv[i + 1]);
  if ((i = ArgPos((char *)"-classes", argc, argv)) > 0) classes = atoi(argv[i + 1]);
  vocab = (struct vocab_word *)calloc(vocab_max_size, sizeof(struct vocab_word));
  vocab_hash = (int *)calloc(vocab_hash_size, sizeof(int));
  expTable = (real *)malloc((EXP_TABLE_SIZE + 1) * sizeof(real));
  for (i = 0; i < EXP_TABLE_SIZE; i++)
  {
	//expTable[i] = exp((i -500)/ 500 * 6)   e^-6 ~ e^6
    expTable[i] = exp((i / (real)EXP_TABLE_SIZE * 2 - 1) * MAX_EXP); // Precompute the exp() table
    //expTable[i] = 1/(1+e^6) ~ 1/(1+e^-6)  0.01 ~ 1    
    expTable[i] = expTable[i] / (expTable[i] + 1);                   // Precompute f(x) = x / (x + 1)
  }
  TrainModel();
  return 0;
}