FastText-THUCNews/Classification/scripts/dataset_utils.py

# coding: UTF-8
import os
import torch
import numpy as np
import pickle as pkl
from tqdm import tqdm
import time
from datetime import timedelta


MAX_VOCAB_SIZE = 10000  # 词表长度限制
UNK, PAD = '<UNK>', '<PAD>'  # 未知字，padding符号


def build_vocab(file_path, tokenizer, max_size, min_freq):
    """构建词汇表"""
    vocab_dic = {}
    with open(file_path, 'r', encoding='UTF-8') as f:
        for line in tqdm(f):
            lin = line.strip()
            if not lin:
                continue
            content = lin.split('\t')[0]
            for word in tokenizer(content):
                vocab_dic[word] = vocab_dic.get(word, 0) + 1
        vocab_list = sorted([_ for _ in vocab_dic.items() if _[1] >= min_freq], key=lambda x: x[1], reverse=True)[:max_size]
        vocab_dic = {word_count[0]: idx for idx, word_count in enumerate(vocab_list)}
        vocab_dic.update({UNK: len(vocab_dic), PAD: len(vocab_dic) + 1})
    return vocab_dic


def load_dataset(path, vocab, tokenizer, pad_size=32):
    """加载数据集"""
    contents = []
    with open(path, 'r', encoding='UTF-8') as f:
        for line in tqdm(f, desc=f"Loading {os.path.basename(path)}"):
            lin = line.strip()
            if not lin:
                continue
            content, label = lin.split('\t')
            words_line = []
            bigram_line = []
            trigram_line = []
            
            token = tokenizer(content)
            seq_len = len(token)
            if pad_size:
                if len(token) < pad_size:
                    token.extend([PAD] * (pad_size - len(token)))
                else:
                    token = token[:pad_size]
                    seq_len = pad_size
            
            # word to id
            for word in token:
                words_line.append(vocab.get(word, vocab.get(UNK)))
            
            # 生成bigram和trigram特征（简化版本，使用hash映射）
            for i in range(len(token)):
                # bigram
                if i < len(token) - 1:
                    bigram = token[i] + token[i+1]
                    bigram_line.append(hash(bigram) % 250499)  # 映射到n_gram_vocab范围内
                else:
                    bigram_line.append(0)  # padding
                
                # trigram
                if i < len(token) - 2:
                    trigram = token[i] + token[i+1] + token[i+2]
                    trigram_line.append(hash(trigram) % 250499)  # 映射到n_gram_vocab范围内
                else:
                    trigram_line.append(0)  # padding
            
            contents.append((words_line, int(label), seq_len, bigram_line, trigram_line))
    return contents


def build_dataset(config, use_word=False):
    """构建数据集"""
    if use_word:
        def tokenizer(x):
            return x.split(' ')  # 以空格隔开，word-level
    else:
        def tokenizer(x):
            return [y for y in x]  # char-level
    
    if os.path.exists(config.vocab_path):
        vocab = pkl.load(open(config.vocab_path, 'rb'))
    else:
        vocab = build_vocab(config.train_path, tokenizer=tokenizer, max_size=MAX_VOCAB_SIZE, min_freq=1)
        pkl.dump(vocab, open(config.vocab_path, 'wb'))
    
    print(f"词汇表大小: {len(vocab)}")
    
    train = load_dataset(config.train_path, vocab, tokenizer, config.pad_size)
    dev = load_dataset(config.dev_path, vocab, tokenizer, config.pad_size)
    test = load_dataset(config.test_path, vocab, tokenizer, config.pad_size)
    
    return vocab, train, dev, test


class DatasetIterator(object):
    """数据集迭代器"""
    def __init__(self, batches, batch_size, device):
        self.batch_size = batch_size
        self.batches = batches
        self.n_batches = len(batches) // batch_size
        self.residue = False  # 记录batch数量是否为整数
        if len(batches) % self.n_batches != 0:
            self.residue = True
        self.index = 0
        self.device = device

    def _to_tensor(self, datas):
        x = torch.LongTensor([_[0] for _ in datas]).to(self.device)
        y = torch.LongTensor([_[1] for _ in datas]).to(self.device)
        # pad前的长度(超过pad_size的设为pad_size)
        seq_len = torch.LongTensor([_[2] for _ in datas]).to(self.device)
        
        # 检查是否有bigram和trigram数据（FastText需要）
        if len(datas[0]) > 3:
            bigram = torch.LongTensor([_[3] for _ in datas]).to(self.device)
            trigram = torch.LongTensor([_[4] for _ in datas]).to(self.device)
            return (x, seq_len, bigram, trigram), y
        else:
            return (x, seq_len), y

    def __next__(self):
        if self.residue and self.index == self.n_batches:
            batches = self.batches[self.index * self.batch_size: len(self.batches)]
            self.index += 1
            batches = self._to_tensor(batches)
            return batches

        elif self.index >= self.n_batches:
            self.index = 0
            raise StopIteration
        else:
            batches = self.batches[self.index * self.batch_size: (self.index + 1) * self.batch_size]
            self.index += 1
            batches = self._to_tensor(batches)
            return batches

    def __iter__(self):
        return self

    def __len__(self):
        if self.residue:
            return self.n_batches + 1
        else:
            return self.n_batches


def build_iterator(dataset, config):
    """构建数据迭代器"""
    iterator = DatasetIterator(dataset, config.batch_size, config.device)
    return iterator


def get_time_dif(start_time):
    """获取已使用时间"""
    end_time = time.time()
    time_dif = end_time - start_time
    return timedelta(seconds=int(round(time_dif)))


def get_labels_from_dataset(dataset):
    """从数据集中提取标签"""
    labels = []
    for _, label, _ in dataset:
        labels.append(label)
    return np.array(labels)