英文电影评论情感分析

分析步骤

数据集

现在我们有一个经典的数据集IMDB数据集，地址：http://ai.stanford.edu/~amaas/data/sentiment/，这是一份包含了5万条流行电影的评论数据，其中训练集25000条，测试集25000条。数据格式如下：

下图左边为名称，其中名称包含两部分，分别是序号和情感评分，（1-4为neg，5-10为pos），右边为评论内容。

 文本预处理

文本是一类序列数据，一篇文章可以看作是字符或单词的序列，本节将介绍文本数据的常见预处理步骤，预处理通常包括四个步骤：

1. 读入文本

2. 分词

3. 建立字典，将每个词映射到一个唯一的索引（index）

4. 将文本从词的序列转换为索引的序列，方便输入模型

文本的tokenization

tokenization就是通常所说的分词，分出的每一个词语我们把它称为token。

常见的分词工具很多，比如：

• jieba分词：https://github.com/fxsjy/jieba

• 清华大学的分词工具THULAC：https://github.com/thunlp/THULAC-Python

构造词典

这里我们可以考虑把文本中的每个词语和其对应的数字，使用字典保存，同时实现方法把句子通过字典映射为包含数字的列表。

实现文本序列化之前，考虑以下几点:

1. 如何使用字典把词语和数字进行对应

2. 不同的词语出现的次数不尽相同，是否需要对高频或者低频词语进行过滤，以及总的词语数量是否需要进行限制

3. 得到词典之后，如何把句子转化为数字序列，如何把数字序列转化为句子

4. 不同句子长度不相同，每个batch的句子如何构造成相同的长度（可以对短句子进行填充，填充特殊字符）

5. 对于新出现的词语在词典中没有出现怎么办（可以使用特殊字符代理）

思路分析：

1. 对所有句子进行分词

2. 词语存入字典，根据次数对词语进行过滤，并统计次数

3. 实现文本转数字序列的方法

4. 实现数字序列转文本方法

# -*-coding:utf-8-*-
import pickle

from tqdm import tqdm

from 情感分析.imdb_sentiment import dataset
# from 情感分析.imdb_sentiment.vocab import Vocab
from torch.utils.data import DataLoader

class Vocab:
    UNK_TAG = "<UNK>"  # 表示未知字符
    PAD_TAG = "<PAD>"  # 填充符
    PAD = 0
    UNK = 1

    def __init__(self):
        self.dict = {  # 保存词语和对应的数字
            self.UNK_TAG: self.UNK,
            self.PAD_TAG: self.PAD
        }
        self.count = {}  # 统计词频的

    def fit(self, sentence):
        """
        接受句子，统计词频
        :param sentence:[str,str,str]
        :return:None
        """
        for word in sentence:
            self.count[word] = self.count.get(word, 0) + 1  # 所有的句子fit之后，self.count就有了所有词语的词频

    def build_vocab(self, min_count=1, max_count=None, max_features=None):
        """
        根据条件构造 词典
        :param min_count:最小词频
        :param max_count: 最大词频
        :param max_features: 最大词语数
        :return:
        """
        if min_count is not None:
            self.count = {word: count for word, count in self.count.items() if count >= min_count}
        if max_count is not None:
            self.count = {word: count for word, count in self.count.items() if count <= max_count}
        if max_features is not None:
            # [(k,v),(k,v)....] --->{k:v,k:v}
            self.count = dict(sorted(self.count.items(), lambda x: x[-1], reverse=True)[:max_features])

        for word in self.count:
            self.dict[word] = len(self.dict)  # 每次word对应一个数字

        # 把dict进行翻转
        self.inverse_dict = dict(zip(self.dict.values(), self.dict.keys()))

    def transform(self, sentence, max_len=None):
        """
        把句子转化为数字序列
        :param sentence:[str,str,str]
        :return: [int,int,int]
        """
        if len(sentence) > max_len:
            sentence = sentence[:max_len]
        else:
            sentence = sentence + [self.PAD_TAG] * (max_len - len(sentence))  # 填充PAD

        return [self.dict.get(i, 1) for i in sentence]

    def inverse_transform(self, incides):
        """
        把数字序列转化为字符
        :param incides: [int,int,int]
        :return: [str,str,str]
        """
        return [self.inverse_dict.get(i, "<UNK>") for i in incides]

    def __len__(self):
        return len(self.dict)

def collate_fn(batch):
    """
    对batch数据进行处理
    :param batch: [一个getitem的结果，getitem的结果,getitem的结果]
    :return: 元组
    """
    reviews, labels = zip(*batch)

    return reviews, labels


def get_dataloader(train=True):
    imdb_dataset = dataset.ImdbDataset(train)
    my_dataloader = DataLoader(imdb_dataset, batch_size=200, shuffle=True, collate_fn=collate_fn)
    return my_dataloader


if __name__ == '__main__':

    # sentences = [["今天", "天气", "很", "好"],
    #              ["今天", "去", "吃", "什么"]]
    # ws = Vocab()
    # for sentence in sentences:
    #     # 统计词频
    #     ws.fit(sentence)
    # # 构造词典
    # ws.build_vocab(min_count=1)
    # print(ws.dict)
    # # 把句子转换成数字序列
    # ret = ws.transform(["好", "好", "好", "好", "好", "好", "好", "热", "呀"], max_len=13)
    # print(ret)
    # # 把数字序列转换成句子
    # ret = ws.inverse_transform(ret)
    # print(ret)
    # pass


    ws = Vocab()
    dl_train = get_dataloader(True)
    dl_test = get_dataloader(False)
    for reviews, label in tqdm(dl_train, total=len(dl_train)):
        for sentence in reviews:
            ws.fit(sentence)
    for reviews, label in tqdm(dl_test, total=len(dl_test)):
        for sentence in reviews:
            ws.fit(sentence)
    ws.build_vocab()
    print(len(ws))

    pickle.dump(ws, open("./models/vocab.pkl", "wb"))

会生成对应的词典pkl文件

构造Dataset与Dataloader

# -*-coding:utf-8-*-
import os
import pickle
import re
import zipfile

from torch.utils.data import Dataset, DataLoader
from tqdm import tqdm

class ImdbDataset(Dataset):
    def __init__(self, train=True):
        # super(ImdbDataset,self).__init__()
        if not os.path.exists("./data/download"):
            unzip_file("./data/test.zip", "./data/download")
            unzip_file("./data/train.zip", "./data/download")
        data_path = r"./data/download"
        data_path += r"/train" if train else r"/test"
        self.total_path = []  # 保存所有的文件路径
        for temp_path in [r"/pos", r"/neg"]:
            cur_path = data_path + temp_path
            self.total_path += [os.path.join(cur_path, i) for i in os.listdir(cur_path) if i.endswith(".txt")]

    def __getitem__(self, idx):
        file = self.total_path[idx]
        # 从txt获取评论并分词
        review = tokenlize(open(file, "r", encoding="utf-8").read())
        # 获取评论对应的label
        label = int(file.split("_")[-1].split(".")[0])
        label = 0 if label < 5 else 1
        return review, label

    def __len__(self):
        return len(self.total_path)


def tokenlize(sentence):
    """
    进行文本分词
    :param sentence: str
    :return: [str,str,str]
    """

    fileters = ['!', '"', '#', '$', '%', '&', '\(', '\)', '\*', '\+', ',', '-', '\.', '/', ':', ';', '<', '=', '>',
                '\?', '@', '\[', '\\', '\]', '^', '_', '`', '\{', '\|', '\}', '~', '\t', '\n', '\x97', '\x96', '”',
                '“', ]
    sentence = sentence.lower()  # 把大写转化为小写
    sentence = re.sub("<br />", " ", sentence)
    # sentence = re.sub("I'm","I am",sentence)
    # sentence = re.sub("isn't","is not",sentence)
    sentence = re.sub("|".join(fileters), " ", sentence)
    result = [i for i in sentence.split(" ") if len(i) > 0]

    return result


def unzip_file(zip_src, dst_dir):
    """
    解压缩
    :param zip_src:
    :param dst_dir:
    :return:
    """
    r = zipfile.is_zipfile(zip_src)
    if r:
        fz = zipfile.ZipFile(zip_src, 'r')
        bar = tqdm(fz.namelist())
        bar.set_description("unzip  " + zip_src)
        for file in bar:
            fz.extract(file, dst_dir)
    else:
        print('This is not zip')


# 以下为调试代码
def collate_fn(batch):
    """
    对batch数据进行处理
    :param batch: [一个getitem的结果，getitem的结果,getitem的结果]
    :return: 元组
    """
    reviews, labels = zip(*batch)

    return reviews, labels

# def test_file(train=True):
#     if not os.path.exists("./data/download"):
#         unzip_file("./data/data.zip", "./data/download")
#     data_path = r"./data/download"
#     data_path += r"/train" if train else r"/test"
#     total_path = []  # 保存所有的文件路径
#     for temp_path in [r"/pos", r"/neg"]:
#         cur_path = data_path + temp_path
#         total_path += [os.path.join(cur_path, i) for i in os.listdir(cur_path) if i.endswith(".txt")]
#     print(total_path)

if __name__ == "__main__":
    from 情感分析.imdb_sentiment.vocab import Vocab
    imdb_dataset = ImdbDataset(True)
    my_dataloader = DataLoader(imdb_dataset, batch_size=2, shuffle=True, collate_fn=collate_fn)
    for review,label in my_dataloader:
        vocab_model = pickle.load(open("./models/vocab.pkl", "rb"))
        print(review[0])
        result = vocab_model.transform(review[0], 100)
        print(result)
        break

    # unzip_file("./data/a.zip", "./data/download")
    # if os.path.exists("./data/download"):
    #     print("T")

    # data = open("./data/download/train/pos\\10032_10.txt", "r", encoding="utf-8").read()
    # result = tokenlize("--or something like that. Who the hell said that theatre stopped at the orchestra pit--or even at the theatre door?")
    # result = tokenlize(data)
    # print(result)

    # test_file()

测试输出：

['this', 'movie', 'was', 'kind', 'of', 'interesting', 'i', 'had', 'to', 'watch', 'it', 'for', 'a', 'college', 'class', 'about', 'india', 'however', 'the', 'synopsis', 'tells', 'you', 'this', 'movie', 'is', 'about', 'one', 'thing', 'when', 'it', "doesn't", 'really', 'contain', 'much', 'cold', 'hard', 'information', 'on', 'those', 'details', 'it', 'is', 'not', 'really', 'true', 'to', 'the', 'synopsis', 'until', 'the', 'very', 'end', 'where', 'they', 'sloppily', 'try', 'to', 'tie', 'all', 'the', 'elements', 'together', 'the', 'gore', 'factor', 'is', 'superb', 'however', 'even', 'right', 'at', 'the', 'very', 'beginning', 'you', 'want', 'to', 'look', 'away', 'because', 'the', 'gore', 'is', 'pretty', 'intense', 'only', 'watch', 'this', 'movie', 'if', 'you', 'want', 'to', 'see', 'some', 'cool', 'gore', 'because', 'the', 'plot', 'is', 'thin', 'and', 'will', 'make', 'you', 'sad', 'that', 'you', 'wasted', 'time', 'listening', 'to', 'it', "i've", 'seen', 'rumors', 'on', 'other', 'websites', 'about', 'this', 'movie', 'being', 'based', 'on', 'true', 'events', 'however', 'you', 'can', 'not', 'find', 'any', 'information', 'about', 'it', 'online', 'so', 'basically', 'this', 'movie', 'was', 'a', 'waste', 'of', 'time', 'to', 'watch']
[2, 3, 93, 390, 14, 181, 90, 136, 100, 312, 7, 17, 78, 5879, 1056, 80, 17356, 117, 18, 6179, 3176, 12, 2, 3, 4, 80, 16, 187, 128, 7, 642, 483, 1011, 314, 987, 1655, 2011, 122, 48, 1176, 7, 4, 8, 483, 496, 100, 18, 6179, 1636, 18, 52, 458, 429, 329, 46669, 2039, 100, 11337, 36, 18, 1366, 753, 18, 2188, 10851, 4, 14736, 117, 9, 855, 58, 18, 52, 2691, 12, 116, 100, 266, 1061, 223, 18, 2188, 4, 819, 371, 308, 312, 2, 3, 11, 12, 116, 100, 46, 65, 710, 2188, 223, 18, 106]

word embedding

word embedding是深度学习中表示文本常用的一种方法。和one-hot编码不同，word embedding使用了浮点型的稠密矩阵来表示token。根据词典的大小，我们的向量通常使用不同的维度，例如100,256,300等。其中向量中的每一个值是一个参数，其初始值是随机生成的，之后会在训练的过程中进行学习而获得。

如果我们文本中有20000个词语，如果使用one-hot编码，那么我们会有20000*20000的矩阵，其中大多数的位置都为0，但是如果我们使用word embedding来表示的话，只需要20000* 维度，比如20000*300

我们会把所有的文本转化为向量，把句子用向量来表示

但是在这中间，我们会先把token使用数字来表示，再把数字使用向量来表示。

即：token---> num ---->vector

 

word embedding API

torch.nn.Embedding(num_embeddings,embedding_dim)

参数介绍：

1. num_embeddings：词典的大小

2. embedding_dim：embedding的维度

使用方法：

embedding = nn.Embedding(vocab_size,300) #实例化

input_embeded = embedding(input)         #进行embedding的操作

embedding模型

# -*-coding:utf-8-*-
import pickle

import torch
import torch.nn as nn
import torch.nn.functional as F
from torch.optim import Adam
from torch.utils.data import DataLoader
from tqdm import tqdm


from 情感分析.imdb_sentiment import dataset
from 情感分析.imdb_sentiment.vocab import Vocab

train_batch_size = 512
test_batch_size = 500
voc_model = pickle.load(open("./models/vocab.pkl", "rb"))
sequence_max_len = 20


def collate_fn(batch):
    """
    对batch数据进行处理
    :param batch: [一个getitem的结果，getitem的结果,getitem的结果]
    :return: 元组
    """
    reviews, labels = zip(*batch)
    reviews = torch.LongTensor([voc_model.transform(i, max_len=sequence_max_len) for i in reviews])
    labels = torch.LongTensor(labels)
    return reviews, labels


def get_dataloader(train=True):
    imdb_dataset = dataset.ImdbDataset(train)
    batch_size = train_batch_size if train else test_batch_size
    return DataLoader(imdb_dataset, batch_size=batch_size, shuffle=True, collate_fn=collate_fn)


class ImdbModel(nn.Module):
    def __init__(self):
        super(ImdbModel, self).__init__()
        self.embedding = nn.Embedding(num_embeddings=len(voc_model), embedding_dim=200,
                                      padding_idx=voc_model.PAD)

        self.fc = nn.Linear(sequence_max_len * 200, 2)

    def forward(self, input):
        """
        :param input:[batch_size,max_len]
        :return:
        """
        input_embeded = self.embedding(input)  # input embeded :[batch_size,max_len,200]

        # 变形
        input_embeded_viewed = input_embeded.view(input_embeded.size(0), -1)

        # 全连接
        out = self.fc(input_embeded_viewed)
        return F.log_softmax(out, dim=-1)


def device():
    if torch.cuda.is_available():
        return torch.device('cuda')
    else:
        return torch.device('cpu')


def train(imdb_model, epoch):
    """

    :param imdb_model:
    :param epoch:
    :return:
    """
    train_dataloader = get_dataloader(train=True)
    # bar = tqdm(train_dataloader, total=len(train_dataloader))

    optimizer = Adam(imdb_model.parameters())
    for i in range(epoch):
        bar = tqdm(train_dataloader, total=len(train_dataloader))
        for idx, (data, target) in enumerate(bar):
            optimizer.zero_grad()
            data = data.to(device())
            target = target.to(device())
            output = imdb_model(data)
            loss = F.nll_loss(output, target)
            loss.backward()
            optimizer.step()
            bar.set_description("epcoh:{}  idx:{}   loss:{:.6f}".format(i, idx, loss.item()))
    torch.save(imdb_model,'fc_model.pkl')


def test(imdb_model):
    """
    验证模型
    :param imdb_model:
    :return:
    """
    test_loss = 0
    correct = 0
    imdb_model.eval()
    test_dataloader = get_dataloader(train=False)
    with torch.no_grad():
        for data, target in tqdm(test_dataloader):
            data = data.to(device())
            target = target.to(device())
            output = imdb_model(data)
            test_loss += F.nll_loss(output, target, reduction='sum').item()
            pred = output.data.max(1, keepdim=True)[1]  # 获取最大值的位置,[batch_size,1]
            correct += pred.eq(target.data.view_as(pred)).sum()
    test_loss /= len(test_dataloader.dataset)
    print('\nTest set: Avg. loss: {:.4f}, Accuracy: {}/{} ({:.2f}%)\n'.format(
        test_loss, correct, len(test_dataloader.dataset),
        100. * correct / len(test_dataloader.dataset)))

#单句测试
def xlftest():
    import numpy as np
    model=torch.load('fc_model.pkl')
    model.to(device())
    from 情感分析.imdb_sentiment.xlftest import tokenlize
    line = open('./data/download/test/neg\\1_3.txt', "r", encoding="utf-8").read()
    print(line)
    review = tokenlize(open('./data/download/test/neg\\1_3.txt', "r", encoding="utf-8").read())
    vocab_model = pickle.load(open("./models/vocab.pkl", "rb"))
    result = vocab_model.transform(review, 20)
    # print(result)
    target=0
    target=torch.LongTensor(target).to(device())
    data=torch.LongTensor(result).to(device())
    data=torch.reshape(data,(1,20))
    print(data.shape)
    output = model(data)
    pred = output.data.max(1, keepdim=True)[1]  # 获取最大值的位置,[batch_size,1]
    #print(pred.item())
    if pred.item()==0:
        print("消极")
    else:
        print("积极")



if __name__ == '__main__':
    imdb_model = ImdbModel().to(device())
    train(imdb_model, 4)
    test(imdb_model)
    xlftest()

会生成对应的模型保存文件

导入可对其进行单独测试

 准确率60%

基于LSTM情感分析

超参数

train_batch_size = 512
test_batch_size = 128
sequence_max_len = 100

模型

class ImdbModel(nn.Module):
    def __init__(self):
        super(ImdbModel, self).__init__()
        self.embedding = nn.Embedding(num_embeddings=len(voc_model), embedding_dim=200, padding_idx=voc_model.PAD).to()
        self.lstm = nn.LSTM(input_size=200, hidden_size=64, num_layers=2, batch_first=True, bidirectional=True,
                            dropout=0.5)
        self.fc1 = nn.Linear(64 * 2, 64)
        self.fc2 = nn.Linear(64, 2)

    def forward(self, input):
        """
        :param input:[batch_size,max_len]
        :return:
        """
        input_embeded = self.embedding(input)  # input embeded :[batch_size,max_len,200]

        output, (h_n, c_n) = self.lstm(input_embeded)  # h_n :[4,batch_size,hidden_size]
        # out :[batch_size,hidden_size*2]
        out = torch.cat([h_n[-1, :, :], h_n[-2, :, :]], dim=-1)  # 拼接正向最后一个输出和反向最后一个输出

        # 进行全连接
        out_fc1 = self.fc1(out)
        # 进行relu
        out_fc1_relu = F.relu(out_fc1)

        # 全连接
        out_fc2 = self.fc2(out_fc1_relu)  # out :[batch_size,2]
        return F.log_softmax(out_fc2, dim=-1)

训练

def train(imdb_model, epoch):
    """

    :param imdb_model:
    :param epoch:
    :return:
    """
    train_dataloader = get_dataloader(train=True)


    optimizer = Adam(imdb_model.parameters())
    for i in range(epoch):
        bar = tqdm(train_dataloader, total=len(train_dataloader))
        for idx, (data, target) in enumerate(bar):
            optimizer.zero_grad()
            data = data.to(device())
            target = target.to(device())
            output = imdb_model(data)
            loss = F.nll_loss(output, target)
            loss.backward()
            optimizer.step()
            bar.set_description("epcoh:{}  idx:{}   loss:{:.6f}".format(i, idx, loss.item()))
    torch.save(imdb_model, 'lstm_model.pkl')

测试

def test(imdb_model):
    """
    验证模型
    :param imdb_model:
    :return:
    """
    test_loss = 0
    correct = 0
    imdb_model.eval()
    test_dataloader = get_dataloader(train=False)
    with torch.no_grad():
        for data, target in tqdm(test_dataloader):
            data = data.to(device())
            target = target.to(device())
            output = imdb_model(data)
            test_loss += F.nll_loss(output, target, reduction='sum').item()
            pred = output.data.max(1, keepdim=True)[1]  # 获取最大值的位置,[batch_size,1]
            correct += pred.eq(target.data.view_as(pred)).sum()
    test_loss /= len(test_dataloader.dataset)
    print('\nTest set: Avg. loss: {:.4f}, Accuracy: {}/{} ({:.2f}%)\n'.format(
        test_loss, correct, len(test_dataloader.dataset),
        100. * correct / len(test_dataloader.dataset)))

单条测试

def xlftest():
    import numpy as np
    model = torch.load('lstm_model.pkl')
    model.to(device())
    from 情感分析.imdb_sentiment.xlftest import tokenlize
    line=open('./data/download/test/neg\\1_3.txt', "r", encoding="utf-8").read()
    print(line)
    review = tokenlize(open('./data/download/test/neg\\1_3.txt', "r", encoding="utf-8").read())
    # review=tokenlize(line)
    vocab_model = pickle.load(open("./models/vocab.pkl", "rb"))
    result = vocab_model.transform(review, 20)
    # print(result)
    target = 0
    target = torch.LongTensor(target).to(device())
    data = torch.LongTensor(result).to(device())
    data = data=torch.reshape(data,(1,20))
    # print(data.shape)
    output = model(data)
    pred = output.data.max(1, keepdim=True)[1]  # 获取最大值的位置,[batch_size,1]
    # print(pred.item())
    if pred.item() == 0:
        print("消极")
    else:
        print("积极")

测试效果

 提升了一些

明日任务

实现中文情感分析