LSTM介绍

RNN问题：长期依赖问题/梯度消失问题
解决：
LSTM
GRU
长短时记忆神经网络LSTN

LSTM是RNN变体，LSTM引入了一组记忆单元（Memory Units），允许网络可以学习何时遗忘历史信息何时用新信息更新记忆单元

四种门

实践任务

本次实践使用基于循环神经网络（RNN）的谣言检测模型，将文本中的谣言事件向量化，通过循环神经网络的学习训练来挖掘表示文本深层的特征，避免了特征构建的问题，并能发现那些不容易被人发现的特征，从而产生更好的效果。

数据集介绍：

本次实践所使用的数据是从新浪微博不实信息举报平台抓取的中文谣言数据，数据集中共包含1538条谣言和1849条非谣言。每条数据均为json格式，其中text字段代表微博原文的文字内容。

数据集介绍参考https://github.com/thunlp/Chinese_Rumor_Dataset

一、环境设置

import paddle
import numpy as np
import matplotlib.pyplot as plt
print(paddle.__version__)

二、数据准备

（1）解压数据，读取并解析数据，生成all_data.txt

（2）生成数据字典，即dict.txt

（3）生成数据列表，并进行训练集与验证集的划分，train_list.txt 、eval_list.txt

（4）定义训练数据集提供器

import os, zipfile
src_path="data/data20519/Rumor_Dataset.zip"
target_path="/home/aistudio/data/Chinese_Rumor_Dataset-master"
if(not os.path.isdir(target_path)):
    z = zipfile.ZipFile(src_path, 'r')
    z.extractall(path=target_path)
    z.close()

import io
import random
import json
#谣言数据文件路径
rumor_class_dirs = os.listdir(target_path+"/Chinese_Rumor_Dataset-master/CED_Dataset/rumor-repost/")

#非谣言数据文件路径
non_rumor_class_dirs = os.listdir(target_path+"/Chinese_Rumor_Dataset-master/CED_Dataset/non-rumor-repost/")

original_microblog = target_path+"/Chinese_Rumor_Dataset-master/CED_Dataset/original-microblog/"

#谣言标签为0，非谣言标签为1
rumor_label="0"
non_rumor_label="1"

#分别统计谣言数据与非谣言数据的总数
rumor_num = 0
non_rumor_num = 0

all_rumor_list = []
all_non_rumor_list = []

#解析谣言数据
for rumor_class_dir in rumor_class_dirs: 
    if(rumor_class_dir != '.DS_Store'):
        #遍历谣言数据，并解析
        with open(original_microblog + rumor_class_dir, 'r') as f:
	        rumor_content = f.read()
        rumor_dict = json.loads(rumor_content)
        all_rumor_list.append(rumor_label+"\t"+rumor_dict["text"]+"\n")
        rumor_num +=1

#解析非谣言数据
for non_rumor_class_dir in non_rumor_class_dirs: 
    if(non_rumor_class_dir != '.DS_Store'):
        with open(original_microblog + non_rumor_class_dir, 'r') as f2:
	        non_rumor_content = f2.read()
        non_rumor_dict = json.loads(non_rumor_content)
        all_non_rumor_list.append(non_rumor_label+"\t"+non_rumor_dict["text"]+"\n")
        non_rumor_num +=1
        
print("谣言数据总量为："+str(rumor_num))
print("非谣言数据总量为："+str(non_rumor_num))

#全部数据进行乱序后写入all_data.txt
data_list_path="/home/aistudio/data/"
all_data_path=data_list_path + "all_data.txt"
all_data_list = all_rumor_list + all_non_rumor_list
random.shuffle(all_data_list)

#在生成all_data.txt之前，首先将其清空
with open(all_data_path, 'w') as f:
    f.seek(0)
    f.truncate() 
    
with open(all_data_path, 'a') as f:
    for data in all_data_list:
        f.write(data) 

# 生成数据字典
def create_dict(data_path, dict_path):
    with open(dict_path, 'w') as f:
        f.seek(0)
        f.truncate() 

    dict_set = set()
    # 读取全部数据
    with open(data_path, 'r', encoding='utf-8') as f:
        lines = f.readlines()
    # 把数据生成一个元组
    for line in lines:
        content = line.split('\t')[-1].replace('\n', '')
        for s in content:
            dict_set.add(s)
    # 把元组转换成字典，一个字对应一个数字
    dict_list = []
    i = 0
    for s in dict_set:
        dict_list.append([s, i])
        i += 1
    # 添加未知字符
    dict_txt = dict(dict_list)
    end_dict = {"<unk>": i}
    dict_txt.update(end_dict)
    end_dict = {"<pad>": i+1}
    dict_txt.update(end_dict)
    # 把这些字典保存到本地中
    with open(dict_path, 'w', encoding='utf-8') as f:
        f.write(str(dict_txt))

    print("数据字典生成完成！")

# 创建序列化表示的数据,并按照一定比例划分训练数据train_list.txt与验证数据eval_list.txt
def create_data_list(data_list_path):
    #在生成数据之前，首先将eval_list.txt和train_list.txt清空
    with open(os.path.join(data_list_path, 'eval_list.txt'), 'w', encoding='utf-8') as f_eval:
        f_eval.seek(0)
        f_eval.truncate()
        
    with open(os.path.join(data_list_path, 'train_list.txt'), 'w', encoding='utf-8') as f_train:
        f_train.seek(0)
        f_train.truncate() 
    
    with open(os.path.join(data_list_path, 'dict.txt'), 'r', encoding='utf-8') as f_data:
        dict_txt = eval(f_data.readlines()[0])

    with open(os.path.join(data_list_path, 'all_data.txt'), 'r', encoding='utf-8') as f_data:
        lines = f_data.readlines()
    
    i = 0
    maxlen = 0
    with open(os.path.join(data_list_path, 'eval_list.txt'), 'a', encoding='utf-8') as f_eval,open(os.path.join(data_list_path, 'train_list.txt'), 'a', encoding='utf-8') as f_train:
        for line in lines:
            words = line.split('\t')[-1].replace('\n', '')
            maxlen = max(maxlen, len(words))
            label = line.split('\t')[0]
            labs = ""
            # 每8个 抽取一个数据用于验证
            if i % 8 == 0:
                for s in words:
                    lab = str(dict_txt[s])
                    labs = labs + lab + ','
                labs = labs[:-1]
                labs = labs + '\t' + label + '\n'
                f_eval.write(labs)
            else:
                for s in words:
                    lab = str(dict_txt[s])
                    labs = labs + lab + ','
                labs = labs[:-1]
                labs = labs + '\t' + label + '\n'
                f_train.write(labs)
            i += 1
        
    print("数据列表生成完成！")
    print("样本最长长度：" + str(maxlen))

谣言数据总量为：1538
非谣言数据总量为：1849

# 把生成的数据列表都放在自己的总类别文件夹中
data_root_path = "/home/aistudio/data/" 
data_path = os.path.join(data_root_path, 'all_data.txt')
dict_path = os.path.join(data_root_path, "dict.txt")

# 创建数据字典
create_dict(data_path, dict_path)

# 创建数据列表
create_data_list(data_root_path)

def load_vocab(file_path):
    fr = open(file_path, 'r', encoding='utf8')
    vocab = eval(fr.read())   #读取的str转换为字典
    fr.close()

    return vocab

# 打印前2条训练数据
vocab = load_vocab(os.path.join(data_root_path, 'dict.txt'))

def ids_to_str(ids):
    words = []
    for k in ids:
        w = list(vocab.keys())[list(vocab.values()).index(int(k))]
        words.append(w if isinstance(w, str) else w.decode('ASCII'))
    return " ".join(words)

file_path = os.path.join(data_root_path, 'train_list.txt')
with io.open(file_path, "r", encoding='utf8') as fin:
        i = 0
        for line in fin:
            i += 1
            cols = line.strip().split("\t")
            if len(cols) != 2:
                sys.stderr.write("[NOTICE] Error Format Line!")
                continue
            label = int(cols[1])
            wids = cols[0].split(",")
            print(str(i)+":")
            print('sentence list id is:', wids)
            print('sentence list is: ', ids_to_str(wids))
            print('sentence label id is:', label)
            print('---------------------------------')
            
            if i == 2: break

vocab = load_vocab(os.path.join(data_root_path, 'dict.txt'))

class RumorDataset(paddle.io.Dataset):
    def __init__(self, data_dir):
        self.data_dir = data_dir
        self.all_data = []
       
        with io.open(self.data_dir, "r", encoding='utf8') as fin:
            for line in fin:
                cols = line.strip().split("\t")
                if len(cols) != 2:
                    sys.stderr.write("[NOTICE] Error Format Line!")
                    continue
                label = []
                label.append(int(cols[1]))
                wids = cols[0].split(",")
                if len(wids)>=150:
                    wids = np.array(wids[:150]).astype('int64')     
                else:
                    wids = np.concatenate([wids, [vocab["<pad>"]]*(150-len(wids))]).astype('int64')
                label = np.array(label).astype('int64')
                self.all_data.append((wids, label))

        
    def __getitem__(self, index):
        data, label = self.all_data[index]
        return data, label

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

batch_size = 32
train_dataset = RumorDataset(os.path.join(data_root_path, 'train_list.txt'))
test_dataset = RumorDataset(os.path.join(data_root_path, 'eval_list.txt'))

train_loader = paddle.io.DataLoader(train_dataset, places=paddle.CPUPlace(), return_list=True,
                                    shuffle=True, batch_size=batch_size, drop_last=True)
test_loader = paddle.io.DataLoader(test_dataset, places=paddle.CPUPlace(), return_list=True,
                                    shuffle=True, batch_size=batch_size, drop_last=True)
#check

print('=============train_dataset =============') 
for data, label in train_dataset:
    print(data)
    print(np.array(data).shape)
    print(label)
    break
    
print('=============test_dataset =============') 
for data, label in test_dataset:
    print(data)
    print(np.array(data).shape)
    print(label)
    break

三、模型配置

import paddle
from paddle.nn import Conv2D, Linear, Embedding
from paddle import to_tensor
import paddle.nn.functional as F

class RNN(paddle.nn.Layer):
    def __init__(self):
        super(RNN, self).__init__()
        self.dict_dim = vocab["<pad>"]
        self.emb_dim = 128
        self.hid_dim = 128
        self.class_dim = 2
        self.embedding = Embedding(
            self.dict_dim + 1, self.emb_dim,
            sparse=False)
        self._fc1 = Linear(self.emb_dim, self.hid_dim)
        self.lstm = paddle.nn.LSTM(self.hid_dim, self.hid_dim)
        self.fc2 = Linear(19200, self.class_dim)

    def forward(self, inputs):
        # [32, 150]
        emb = self.embedding(inputs)
        # [32, 150, 128]
        fc_1 = self._fc1(emb)#第一层
        # [32, 150, 128]
        x = self.lstm(fc_1)
        x = paddle.reshape(x[0], [0, -1])
        x = self.fc2(x)
        x = paddle.nn.functional.softmax(x)
        return x

rnn = RNN()
paddle.summary(rnn,(32,150),"int64")

四、模型训练

def draw_process(title,color,iters,data,label):
    plt.title(title, fontsize=24)
    plt.xlabel("iter", fontsize=20)
    plt.ylabel(label, fontsize=20)
    plt.plot(iters, data,color=color,label=label) 
    plt.legend()
    plt.grid()
    plt.show()

def train(model):
    model.train()
    opt = paddle.optimizer.Adam(learning_rate=0.002, parameters=model.parameters())
    
    steps = 0
    Iters, total_loss, total_acc = [], [], []
    
    for epoch in range(3):
        for batch_id, data in enumerate(train_loader):
            steps += 1
            sent = data[0]
            label = data[1]
            
            logits = model(sent)
            loss = paddle.nn.functional.cross_entropy(logits, label)
            acc = paddle.metric.accuracy(logits, label)

            if batch_id % 50 == 0:
                Iters.append(steps)
                total_loss.append(loss.numpy()[0])
                total_acc.append(acc.numpy()[0])

                print("epoch: {}, batch_id: {}, loss is: {}".format(epoch, batch_id, loss.numpy()))
            
            loss.backward()
            opt.step()
            opt.clear_grad()

        # evaluate model after one epoch
        model.eval()
        accuracies = []
        losses = []
        
        for batch_id, data in enumerate(test_loader):
            
            sent = data[0]
            label = data[1]

            logits = model(sent)
            loss = paddle.nn.functional.cross_entropy(logits, label)
            acc = paddle.metric.accuracy(logits, label)
            
            accuracies.append(acc.numpy())
            losses.append(loss.numpy())
        
        avg_acc, avg_loss = np.mean(accuracies), np.mean(losses)

        print("[validation] accuracy: {}, loss: {}".format(avg_acc, avg_loss))
        
        model.train()

    paddle.save(model.state_dict(),"model_final.pdparams")
    
    draw_process("trainning loss","red",Iters,total_loss,"trainning loss")
    draw_process("trainning acc","green",Iters,total_acc,"trainning acc")
        
model = RNN()
train(model)

五、模型评估

'''
模型评估
'''
model_state_dict = paddle.load('model_final.pdparams')
model = RNN()
model.set_state_dict(model_state_dict) 
model.eval()
label_map = {0:"是", 1:"否"}
samples = []
predictions = []
accuracies = []
losses = []

for batch_id, data in enumerate(test_loader):
    
    sent = data[0]
    label = data[1]

    logits = model(sent)

    for idx,probs in enumerate(logits):
        # 映射分类label
        label_idx = np.argmax(probs)
        labels = label_map[label_idx]
        predictions.append(labels)
        samples.append(sent[idx].numpy())
    
    loss = paddle.nn.functional.cross_entropy(logits, label)
    acc = paddle.metric.accuracy(logits, label)
    
    accuracies.append(acc.numpy())
    losses.append(loss.numpy())

avg_acc, avg_loss = np.mean(accuracies), np.mean(losses)
print("[validation] accuracy: {}, loss: {}".format(avg_acc, avg_loss))
print('数据: {} \n\n是否谣言: {}'.format(ids_to_str(samples[0]), predictions[0]))