基于pytorch构建双向LSTM（Bi-LSTM）文本情感分类实例

学长给的代码，感觉结构清晰，还是蛮不错的，想以后就照着这样的结构走好了，记录一下。

首先配置环境

matplotlib==3.4.2
numpy==1.20.3
pandas==1.3.0
sklearn==0.0
spacy==3.1.2
torch==1.8.0
TorchSnooper==0.8
tqdm==4.61.0

也不一定要完全一样，到时候哪里报错就改哪里就好了

数据集
https://download.csdn.net/download/qq_52785473/79483740
上传到资源里，设置的是0积分下载

下载之后创建一个datasets文件夹解压到里面就好了，或者改改代码也行。

首先创建配置文件config.py

class my_config():
    max_length = 20  # 每句话截断长度
    batch_size = 64  # 一个batch的大小
    embedding_size = 256  # 词向量大小
    hidden_size = 128  # 隐藏层大小
    num_layers = 2  # 网络层数
    dropout = 0.5  # 遗忘程度
    output_size = 2  # 输出大小
    lr = 0.001  # 学习率
    epoch = 5  # 训练次数

再创建dataset.py

import pandas as pd
import os
import torchtext
from tqdm import tqdm


class mydata(object):
    def __init__(self):
        self.data_dir = './datasets'
        self.n_class = 2

    def _generator(self, filename):  # 加载每行数据及其标签
        path = os.path.join(self.data_dir, filename)
        df = pd.read_csv(path, sep='\t', header=None)
        for index, line in df.iterrows():
            sentence = line[0]
            label = line[1]
            yield sentence, label

    def load_train_data(self):  # 加载数据
        return self._generator('train.tsv')

    def load_dev_data(self):
        return self._generator('dev.tsv')

    def load_test_data(self):
        return self._generator('test.tsv')


class Dataset(object):
    def __init__(self, dataset: mydata, config):
        self.dataset = dataset
        self.config = config  # 配置文件

    def load_data(self):
        tokenizer = lambda sentence: [x for x in sentence.split() if x != ' ']  # 以空格切词
        # 定义field
        TEXT = torchtext.data.Field(sequential=True, tokenize=tokenizer, lower=True, fix_length=self.config.max_length)
        LABEL = torchtext.data.Field(sequential=False, use_vocab=False)

        # text, label能取出example对应的数据
        # 相当于定义了一种数据类型吧
        datafield = [("text", TEXT), ("label", LABEL)]

        # 加载数据
        train_gen = self.dataset.load_train_data()
        dev_gen = self.dataset.load_dev_data()
        test_gen = self.dataset.load_test_data()

        # 转换数据为example对象（数据+标签）
        train_example = [torchtext.data.Example.fromlist(it, datafield) for it in tqdm(train_gen)]
        dev_example = [torchtext.data.Example.fromlist(it, datafield) for it in tqdm(dev_gen)]
        test_example = [torchtext.data.Example.fromlist(it, datafield) for it in tqdm(test_gen)]

        # 转换成dataset
        train_data = torchtext.data.Dataset(train_example, datafield)  # example, field传入
        dev_data = torchtext.data.Dataset(dev_example, datafield)
        test_data = torchtext.data.Dataset(test_example, datafield)

        # 训练集创建字典，默认添加两个特殊字符和
        TEXT.build_vocab(train_data)
        # 获取字典大小
        self.vocab = TEXT.vocab

        # 放入迭代器并打包成batch及按元素个数排序，到时候直接调用即可
        self.train_iterator = torchtext.data.BucketIterator(
            (train_data),
            batch_size=self.config.batch_size,
            sort_key=lambda x: len(x.text),
            shuffle=False
        )

        self.dev_iterator, self.test_iterator = torchtext.data.BucketIterator.splits(
            (dev_data, test_data),
            batch_size=self.config.batch_size,
            sort_key=lambda x: len(x.text),
            repeat=False
        )

        print(f"load {len(train_data)} training examples")
        print(f"load {len(dev_data)} dev examples")
        print(f"load {len(test_data)} test examples")

再创建model.py

import torch
import torch.nn as nn
from config import my_config


class myLSTM(nn.Module):
    def __init__(self, vocab_size, config: my_config):
        super(myLSTM, self).__init__()  # 初始化
        self.vocab_size = vocab_size
        self.config = config
        self.embeddings = nn.Embedding(vocab_size, self.config.embedding_size)  # 配置嵌入层，计算出词向量
        self.lstm = nn.LSTM(
            input_size=self.config.embedding_size,  # 输入大小为转化后的词向量
            hidden_size=self.config.hidden_size,  # 隐藏层大小
            num_layers=self.config.num_layers,  # 堆叠层数，有几层隐藏层就有几层
            dropout=self.config.dropout,  # 遗忘门参数
            bidirectional=True  # 双向LSTM
        )

        self.dropout = nn.Dropout(self.config.dropout)
        self.fc = nn.Linear(
            self.config.num_layers * self.config.hidden_size * 2,  # 因为双向所有要*2
            self.config.output_size
        )

        self.softmax = nn.Softmax(dim=-1)

    def forward(self, x):
        embedded = self.embeddings(x)

        lstm_out, (h_n, c_n) = self.lstm(embedded)

        feature = self.dropout(h_n)

        # 这里将所有隐藏层进行拼接来得出输出结果，没有使用模型的输出
        feature_map = torch.cat([feature[i, :, :] for i in range(feature.shape[0])], dim=-1)

        out = self.fc(feature_map)

        return self.softmax(out)

最后创建training.py

from dataset import mydata, Dataset
from model import myLSTM
from config import my_config
import torch
import torch.nn as nn
import numpy as np
from sklearn.metrics import accuracy_score
import matplotlib.pyplot as plt


def run_epoch(model, train_iterator, dev_iterator, optimzer, loss_fn):  # 训练模型
    '''
    :param model:模型
    :param train_iterator:训练数据的迭代器
    :param dev_iterator: 验证数据的迭代器
    :param optimzer: 优化器
    :param loss_fn: 损失函数
    '''
    losses = []
    for i, batch in enumerate(train_iterator):
        if torch.cuda.is_available():
            input = batch.text.cuda()
            label = batch.label.type(torch.cuda.LongTensor)
        else:
            input = batch.text
            label = batch.label

        pred = model(input)  # 预测
        loss = loss_fn(pred, label)  # 计算损失值
        loss.backward()  # 误差反向传播
        losses.append(loss.data.numpy())  # 记录误差
        optimzer.step()  # 优化一次

        # if i % 30 == 0:  # 训练30个batch后查看损失值和准确率
        #     avg_train_loss = np.mean(losses)
        #     print(f'iter:{i + 1},avg_train_loss:{avg_train_loss:.4f}')
        #     losses = []
        #     val_acc = evaluate_model(model, dev_iterator)
        #     print('val_acc:{:.4f}'.format(val_acc))
        #     model.train()


def evaluate_model(model, dev_iterator):  # 评价模型
    '''
    :param model:模型
    :param dev_iterator:待评价的数据
    :return:评价（准确率）
    '''
    all_pred = []
    all_y = []
    for i, batch in enumerate(dev_iterator):
        if torch.cuda.is_available():
            input = batch.text.cuda()
            label = batch.label.type(torch.cuda.LongTensor)
        else:
            input = batch.text
            label = batch.label

        y_pred = model(input)  # 预测
        predicted = torch.max(y_pred.cpu().data, 1)[1]  # 选择概率最大作为当前数据预测结果
        all_pred.extend(predicted.numpy())
        all_y.extend(label.numpy())
    score = accuracy_score(all_y, np.array(all_pred).flatten())  # 计算准确率
    return score


if __name__ == '__main__':
    config = my_config()  # 配置对象实例化
    data_class = mydata()  # 数据类实例化
    config.output_size = data_class.n_class
    dataset = Dataset(data_class, config)  # 数据预处理实例化

    dataset.load_data()  # 进行数据预处理

    train_iterator = dataset.train_iterator  # 得到处理好的数据迭代器
    dev_iterator = dataset.dev_iterator
    test_iterator = dataset.test_iterator

    vocab_size = len(dataset.vocab)  # 字典大小

    # 初始化模型
    model = myLSTM(vocab_size, config)

    optimzer = torch.optim.Adam(model.parameters(), lr=config.lr)  # 优化器
    loss_fn = nn.CrossEntropyLoss()  # 交叉熵损失函数

    y = []
    for i in range(config.epoch):
        print(f'epoch:{i + 1}')
        run_epoch(model, train_iterator, dev_iterator, optimzer, loss_fn)

        # 训练一次后评估一下模型
        train_acc = evaluate_model(model, train_iterator)
        dev_acc = evaluate_model(model, dev_iterator)
        test_acc = evaluate_model(model, test_iterator)

        print('#' * 20)
        print('train_acc:{:.4f}'.format(train_acc))
        print('dev_acc:{:.4f}'.format(dev_acc))
        print('test_acc:{:.4f}'.format(test_acc))

        y.append(test_acc)
    # 训练完画图
    x = [i for i in range(len(y))]
    fig = plt.figure()
    plt.plot(x, y)
    plt.show()

最后应该是这样

最后运行training就可以跑模型了。
至于模型的保存和之后的调用
可以参考关于pytorch模型保存与调用的一种方法及一些坑。
稍微改改就好了。