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    python通过Seq2Seq实现闲聊机器人

    作者:IT之一小佬 时间:2021-07-02 18:42

    目录
    • 一、准备训练数据
    • 二、数据的处理和保存
      • 2.1 小黄鸡的语料的处理
      • 2.2 微博语料的处理
      • 2.3 处理后的结果
    • 三、构造文本序列化和反序列化方法
      • 四、构建Dataset和DataLoader
        • 五、完成encoder编码器逻辑
          • 六、完成decoder解码器的逻辑
            • 七、完成seq2seq的模型
              • 八、完成训练逻辑
                • 九、评估逻辑

                  一、准备训练数据

                  主要的数据有两个:

                  1.小黄鸡的聊天语料:噪声很大

                  2.微博的标题和评论:质量相对较高

                  二、数据的处理和保存

                  由于数据中存到大量的噪声,可以对其进行基础的处理,然后分别把input和target使用两个文件保存,即input中的第N行尾问,target的第N行为答

                  后续可能会把单个字作为特征(存放在input_word.txt),也可能会把词语作为特征(input.txt)

                  2.1 小黄鸡的语料的处理

                  def format_xiaohuangji_corpus(word=False):
                      """处理小黄鸡的语料"""
                      if word:
                          corpus_path = "./chatbot/corpus/xiaohuangji50w_nofenci.conv"
                          input_path = "./chatbot/corpus/input_word.txt"
                          output_path = "./chatbot/corpus/output_word.txt"
                      else:
                   
                          corpus_path = "./chatbot/corpus/xiaohuangji50w_nofenci.conv"
                          input_path = "./chatbot/corpus/input.txt"
                          output_path = "./chatbot/corpus/output.txt"
                   
                      f_input = open(input_path, "a")
                      f_output = open(output_path, "a")
                      pair = []
                      for line in tqdm(open(corpus_path), ascii=True):
                          if line.strip() == "E":
                              if not pair:
                                  continue
                              else:
                                  assert len(pair) == 2, "长度必须是2"
                                  if len(pair[0].strip()) >= 1 and len(pair[1].strip()) >= 1:
                                      f_input.write(pair[0] + "\n")
                                      f_output.write(pair[1] + "\n")
                                  pair = []
                          elif line.startswith("M"):
                              line = line[1:]
                              if word:
                                  pair.append(" ".join(list(line.strip())))
                              else:
                                  pair.append(" ".join(jieba_cut(line.strip())))
                  

                  2.2 微博语料的处理

                  def format_weibo(word=False):
                      """
                      微博数据存在一些噪声,未处理
                      :return:
                      """
                      if word:
                          origin_input = "./chatbot/corpus/stc_weibo_train_post"
                          input_path = "./chatbot/corpus/input_word.txt"
                   
                          origin_output = "./chatbot/corpus/stc_weibo_train_response"
                          output_path = "./chatbot/corpus/output_word.txt"
                   
                      else:
                          origin_input = "./chatbot/corpus/stc_weibo_train_post"
                          input_path = "./chatbot/corpus/input.txt"
                   
                          origin_output = "./chatbot/corpus/stc_weibo_train_response"
                          output_path = "./chatbot/corpus/output.txt"
                   
                      f_input = open(input_path, "a")
                      f_output = open(output_path, "a")
                      with open(origin_input) as in_o, open(origin_output) as out_o:
                          for _in, _out in tqdm(zip(in_o, out_o), ascii=True):
                              _in = _in.strip()
                              _out = _out.strip()
                   
                              if _in.endswith(")") or _in.endswith("」") or _in.endswith(")"):
                                  _in = re.sub("(.*)|「.*?」|\(.*?\)", " ", _in)
                              _in = re.sub("我在.*?alink|alink|(.*?\d+x\d+.*?)|#|】|【|-+|_+|via.*?:*.*", " ", _in)
                   
                              _in = re.sub("\s+", " ", _in)
                              if len(_in) < 1 or len(_out) < 1:
                                  continue
                   
                              if word:
                                  _in = re.sub("\s+", "", _in)  # 转化为一整行,不含空格
                                  _out = re.sub("\s+", "", _out)
                                  if len(_in) >= 1 and len(_out) >= 1:
                                      f_input.write(" ".join(list(_in)) + "\n")
                                      f_output.write(" ".join(list(_out)) + "\n")
                              else:
                                  if len(_in) >= 1 and len(_out) >= 1:
                                      f_input.write(_in.strip() + "\n")
                                      f_output.write(_out.strip() + "\n")
                   
                      f_input.close()
                      f_output.close()
                  

                  2.3 处理后的结果

                  三、构造文本序列化和反序列化方法

                  和之前的操作相同,需要把文本能转化为数字,同时还需实现方法把数字转化为文本

                  示例代码:

                  import config
                  import pickle
                   
                   
                  class Word2Sequence():
                      UNK_TAG = "UNK"
                      PAD_TAG = "PAD"
                      SOS_TAG = "SOS"
                      EOS_TAG = "EOS"
                   
                      UNK = 0
                      PAD = 1
                      SOS = 2
                      EOS = 3
                   
                      def __init__(self):
                          self.dict = {
                              self.UNK_TAG: self.UNK,
                              self.PAD_TAG: self.PAD,
                              self.SOS_TAG: self.SOS,
                              self.EOS_TAG: self.EOS
                          }
                          self.count = {}
                          self.fited = False
                   
                      def to_index(self, word):
                          """word -> index"""
                          assert self.fited == True, "必须先进行fit操作"
                          return self.dict.get(word, self.UNK)
                   
                      def to_word(self, index):
                          """index -> word"""
                          assert self.fited, "必须先进行fit操作"
                          if index in self.inversed_dict:
                              return self.inversed_dict[index]
                          return self.UNK_TAG
                   
                      def __len__(self):
                          return len(self.dict)
                   
                      def fit(self, sentence):
                          """
                          :param sentence:[word1,word2,word3]
                          :param min_count: 最小出现的次数
                          :param max_count: 最大出现的次数
                          :param max_feature: 总词语的最大数量
                          :return:
                          """
                          for a in sentence:
                              if a not in self.count:
                                  self.count[a] = 0
                              self.count[a] += 1
                   
                          self.fited = True
                   
                      def build_vocab(self, min_count=1, max_count=None, max_feature=None):
                   
                          # 比最小的数量大和比最大的数量小的需要
                          if min_count is not None:
                              self.count = {k: v for k, v in self.count.items() if v >= min_count}
                          if max_count is not None:
                              self.count = {k: v for k, v in self.count.items() if v <= max_count}
                   
                          # 限制最大的数量
                          if isinstance(max_feature, int):
                              count = sorted(list(self.count.items()), key=lambda x: x[1])
                              if max_feature is not None and len(count) > max_feature:
                                  count = count[-int(max_feature):]
                              for w, _ in count:
                                  self.dict[w] = len(self.dict)
                          else:
                              for w in sorted(self.count.keys()):
                                  self.dict[w] = len(self.dict)
                   
                          # 准备一个index->word的字典
                          self.inversed_dict = dict(zip(self.dict.values(), self.dict.keys()))
                   
                      def transform(self, sentence, max_len=None, add_eos=False):
                          """
                          实现吧句子转化为数组(向量)
                          :param sentence:
                          :param max_len:
                          :return:
                          """
                          assert self.fited, "必须先进行fit操作"
                   
                          r = [self.to_index(i) for i in sentence]
                          if max_len is not None:
                              if max_len > len(sentence):
                                  if add_eos:
                                      r += [self.EOS] + [self.PAD for _ in range(max_len - len(sentence) - 1)]
                                  else:
                                      r += [self.PAD for _ in range(max_len - len(sentence))]
                              else:
                                  if add_eos:
                                      r = r[:max_len - 1]
                                      r += [self.EOS]
                                  else:
                                      r = r[:max_len]
                          else:
                              if add_eos:
                                  r += [self.EOS]
                          # print(len(r),r)
                          return r
                   
                      def inverse_transform(self, indices):
                          """
                          实现从数组 转化为 向量
                          :param indices: [1,2,3....]
                          :return:[word1,word2.....]
                          """
                          sentence = []
                          for i in indices:
                              word = self.to_word(i)
                              sentence.append(word)
                          return sentence
                   
                   
                  # 之后导入该word_sequence使用
                  word_sequence = pickle.load(open("./pkl/ws.pkl", "rb")) if not config.use_word else pickle.load(
                      open("./pkl/ws_word.pkl", "rb"))
                   
                  if __name__ == '__main__':
                      from word_sequence import Word2Sequence
                      from tqdm import tqdm
                      import pickle
                   
                      word_sequence = Word2Sequence()
                      # 词语级别
                      input_path = "../corpus/input.txt"
                      target_path = "../corpus/output.txt"
                      for line in tqdm(open(input_path).readlines()):
                          word_sequence.fit(line.strip().split())
                      for line in tqdm(open(target_path).readlines()):
                          word_sequence.fit(line.strip().split())
                   
                      # 使用max_feature=5000个数据
                      word_sequence.build_vocab(min_count=5, max_count=None, max_feature=5000)
                      print(len(word_sequence))
                      pickle.dump(word_sequence, open("./pkl/ws.pkl", "wb"))
                  

                  word_sequence.py:

                  class WordSequence(object):
                      PAD_TAG = 'PAD'  # 填充标记
                      UNK_TAG = 'UNK'  # 未知词标记
                      SOS_TAG = 'SOS'  # start of sequence
                      EOS_TAG = 'EOS'  # end of sequence
                   
                      PAD = 0
                      UNK = 1
                      SOS = 2
                      EOS = 3
                   
                      def __init__(self):
                          self.dict = {
                              self.PAD_TAG: self.PAD,
                              self.UNK_TAG: self.UNK,
                              self.SOS_TAG: self.SOS,
                              self.EOS_TAG: self.EOS
                          }
                          self.count = {}  # 保存词频词典
                          self.fited = False
                   
                      def to_index(self, word):
                          """
                          word --> index
                          :param word:
                          :return:
                          """
                          assert self.fited == True, "必须先进行fit操作"
                          return self.dict.get(word, self.UNK)
                   
                      def to_word(self, index):
                          """
                          index -- > word
                          :param index:
                          :return:
                          """
                          assert self.fited, '必须先进行fit操作'
                          if index in self.inverse_dict:
                              return self.inverse_dict[index]
                          return self.UNK_TAG
                   
                      def fit(self, sentence):
                          """
                          传入句子,统计词频
                          :param sentence:
                          :return:
                          """
                          for word in sentence:
                              # 对word出现的频率进行统计,当word不在sentence时,返回值是0,当word在sentence中时,返回+1,以此进行累计计数
                              # self.count[word] = self.dict.get(word, 0) + 1
                              if word not in self.count:
                                  self.count[word] = 0
                              self.count[word] += 1
                          self.fited = True
                   
                      def build_vocab(self, min_count=2, max_count=None, max_features=None):
                          """
                          构造词典
                          :param min_count:最小词频
                          :param max_count: 最大词频
                          :param max_features: 词典中词的数量
                          :return:
                          """
                          # self.count.pop(key),和del self.count[key] 无法在遍历self.count的同时进行删除key.因此浅拷贝temp后对temp遍历并删除self.count
                          temp = self.count.copy()
                          for key in temp:
                              cur_count = self.count.get(key, 0)  # 当前词频
                              if min_count is not None:
                                  if cur_count < min_count:
                                      del self.count[key]
                              if max_count is not None:
                                  if cur_count > max_count:
                                      del self.count[key]
                              if max_features is not None:
                                  self.count = dict(sorted(list(self.count.items()), key=lambda x: x[1], reversed=True)[:max_features])
                          for key in self.count:
                              self.dict[key] = len(self.dict)
                          #  准备一个index-->word的字典
                          self.inverse_dict = dict(zip(self.dict.values(), self.dict.keys()))
                   
                      def transforms(self, sentence, max_len=10, add_eos=False):
                          """
                          把sentence转化为序列
                          :param sentence: 传入的句子
                          :param max_len: 句子的最大长度
                          :param add_eos: 是否添加结束符
                          add_eos : True时,输出句子长度为max_len + 1
                          add_eos : False时,输出句子长度为max_len
                          :return:
                          """
                          assert self.fited, '必须先进行fit操作!'
                          if len(sentence) > max_len:
                              sentence = sentence[:max_len]
                          #  提前计算句子长度,实现ass_eos后,句子长度统一
                          sentence_len = len(sentence)
                          #  sentence[1,3,4,5,UNK,EOS,PAD,....]
                          if add_eos:
                              sentence += [self.EOS_TAG]
                          if sentence_len < max_len:
                              #  句子长度不够,用PAD来填充
                              sentence += (max_len - sentence_len) * [self.PAD_TAG]
                          #  对于新出现的词采用特殊标记
                          result = [self.dict.get(i, self.UNK) for i in sentence]
                   
                          return result
                   
                      def invert_transform(self, indices):
                          """
                          序列转化为sentence
                          :param indices:
                          :return:
                          """
                          # return [self.inverse_dict.get(i, self.UNK_TAG) for i in indices]
                          result = []
                          for i in indices:
                              if self.inverse_dict[i] == self.EOS_TAG:
                                  break
                              result.append(self.inverse_dict.get(i, self.UNK_TAG))
                          return result
                   
                      def __len__(self):
                          return len(self.dict)
                   
                   
                  if __name__ == '__main__':
                      num_sequence = WordSequence()
                      print(num_sequence.dict)
                      str1 = ['中国', '您好', '我爱你', '中国', '我爱你', '北京']
                      num_sequence.fit(str1)
                      num_sequence.build_vocab()
                      print(num_sequence.transforms(str1))
                      print(num_sequence.dict)
                      print(num_sequence.inverse_dict)
                      print(num_sequence.invert_transform([5, 4]))  # 这儿要传列表
                  

                  运行结果:

                  四、构建Dataset和DataLoader

                  创建dataset.py 文件,准备数据集

                  import config
                  import torch
                  from torch.utils.data import Dataset, DataLoader
                  from word_sequence import WordSequence
                   
                   
                  class ChatDataset(Dataset):
                      def __init__(self):
                          self.input_path = config.chatbot_input_path
                          self.target_path = config.chatbot_target_path
                          self.input_lines = open(self.input_path, encoding='utf-8').readlines()
                          self.target_lines = open(self.target_path, encoding='utf-8').readlines()
                          assert len(self.input_lines) == len(self.target_lines), 'input和target长度不一致'
                   
                      def __getitem__(self, item):
                          input = self.input_lines[item].strip().split()
                          target = self.target_lines[item].strip().split()
                          if len(input) == 0 or len(target) == 0:
                              input = self.input_lines[item + 1].strip().split()
                              target = self.target_lines[item + 1].strip().split()
                          # 此处句子的长度如果大于max_len,那么应该返回max_len
                          input_length = min(len(input), config.max_len)
                          target_length = min(len(target), config.max_len)
                          return input, target, input_length, target_length
                   
                      def __len__(self):
                          return len(self.input_lines)
                   
                   
                  def collate_fn(batch):
                      #  1.排序
                      batch = sorted(batch, key=lambda x: x[2], reversed=True)
                      input, target, input_length, target_length = zip(*batch)
                   
                      #  2.进行padding的操作
                      input = torch.LongTensor([WordSequence.transform(i, max_len=config.max_len) for i in input])
                      target = torch.LongTensor([WordSequence.transforms(i, max_len=config.max_len, add_eos=True) for i in target])
                      input_length = torch.LongTensor(input_length)
                      target_length = torch.LongTensor(target_length)
                   
                      return input, target, input_length, target_length
                   
                   
                  data_loader = DataLoader(dataset=ChatDataset(), batch_size=config.batch_size, shuffle=True, collate_fn=collate_fn,
                                           drop_last=True)
                   
                   
                  if __name__ == '__main__':
                      print(len(data_loader))
                      for idx, (input, target, input_length, target_length) in enumerate(data_loader):
                          print(idx)
                          print(input)
                          print(target)
                          print(input_length)
                          print(target_length)
                  

                  五、完成encoder编码器逻辑

                  encode.py:

                  import torch.nn as nn
                  import config
                  from torch.nn.utils.rnn import pad_packed_sequence, pack_padded_sequence
                   
                   
                  class Encoder(nn.Module):
                      def __init__(self):
                          super(Encoder, self).__init__()
                          #  torch.nn.Embedding(num_embeddings词典大小即不重复词数,embedding_dim单个词用多长向量表示)
                          self.embedding = nn.Embedding(
                              num_embeddings=len(config.word_sequence.dict),
                              embedding_dim=config.embedding_dim,
                              padding_idx=config.word_sequence.PAD
                          )
                          self.gru = nn.GRU(
                              input_size=config.embedding_dim,
                              num_layers=config.num_layer,
                              hidden_size=config.hidden_size,
                              bidirectional=False,
                              batch_first=True
                          )
                   
                      def forward(self, input, input_length):
                          """
                          :param input: [batch_size, max_len]
                          :return:
                          """
                          embedded = self.embedding(input)  # embedded [batch_size, max_len, embedding_dim]
                          # 加速循环过程
                          embedded = pack_padded_sequence(embedded, input_length, batch_first=True)  # 打包
                          out, hidden = self.gru(embedded)
                          out, out_length = pad_packed_sequence(out, batch_first=True, padding_value=config.num_sequence.PAD)  # 解包
                   
                          # hidden即h_n [num_layer*[1/2],batchsize, hidden_size]
                          # out : [batch_size, seq_len/max_len, hidden_size]
                          return out, hidden, out_length
                   
                   
                  if __name__ == '__main__':
                      from dataset import data_loader
                   
                      encoder = Encoder()
                      print(encoder)
                      for input, target, input_length, target_length in data_loader:
                          out, hidden, out_length = encoder(input, input_length)
                          print(input.size())
                          print(out.size())
                          print(hidden.size())
                          print(out_length)
                          break
                  

                  六、完成decoder解码器的逻辑

                  decode.py:

                  import torch
                  import torch.nn as nn
                  import config
                  import torch.nn.functional as F
                  from word_sequence import WordSequence
                   
                   
                  class Decode(nn.Module):
                      def __init__(self):
                          super().__init__()
                          self.max_seq_len = config.max_len
                          self.vocab_size = len(WordSequence)
                          self.embedding_dim = config.embedding_dim
                          self.dropout = config.dropout
                   
                          self.embedding = nn.Embedding(num_embeddings=self.vocab_size, embedding_dim=self.embedding_dim,
                                                        padding_idx=WordSequence.PAD)
                          self.gru = nn.GRU(input_size=self.embedding_dim, hidden_size=config.hidden_size, num_layers=1, batch_first=True,
                                            dropout=self.dropout)
                          self.log_softmax = nn.LogSoftmax()
                          self.fc = nn.Linear(config.hidden_size, self.vocab_size)
                   
                      def forward(self, encoder_hidden, target, target_length):
                          # encoder_hidden [batch_size,hidden_size]
                          # target [batch_size,seq-len]
                          decoder_input = torch.LongTensor([[WordSequence.SOS]] * config.batch_size).to(config.device)
                          decoder_outputs = torch.zeros(config.batch_size, config.max_len, self.vocab_size).to(
                              config.device)  # [batch_size,seq_len,14]
                   
                          decoder_hidden = encoder_hidden  # [batch_size,hidden_size]
                   
                          for t in range(config.max_len):
                              decoder_output_t, decoder_hidden = self.forward_step(decoder_input, decoder_hidden)
                              decoder_outputs[:, t, :] = decoder_output_t
                              value, index = torch.topk(decoder_output_t, 1)  # index [batch_size,1]
                              decoder_input = index
                          return decoder_outputs, decoder_hidden
                   
                      def forward_step(self, decoder_input, decoder_hidden):
                          """
                          :param decoder_input:[batch_size,1]
                          :param decoder_hidden:[1,batch_size,hidden_size]
                          :return:[batch_size,vocab_size],decoder_hidden:[1,batch_size,didden_size]
                          """
                          embeded = self.embedding(decoder_input)  # embeded: [batch_size,1 , embedding_dim]
                          out, decoder_hidden = self.gru(embeded, decoder_hidden)  # out [1, batch_size, hidden_size]
                          out = out.squeeze(0)
                          out = F.log_softmax(self.fc(out), dim=1)  # [batch_Size, vocab_size]
                          out = out.squeeze(0)
                          # print("out size:",out.size(),decoder_hidden.size())
                          return out, decoder_hidden
                  

                  关于 decoder_outputs[:,t,:] = decoder_output_t的演示

                  decoder_outputs 形状 [batch_size, seq_len, vocab_size]
                  decoder_output_t 形状[batch_size, vocab_size]

                  示例代码:

                  import torch
                   
                  a = torch.zeros((2, 3, 5))
                  print(a.size())
                  print(a)
                   
                  b = torch.randn((2, 5))
                  print(b.size())
                  print(b)
                   
                  a[:, 0, :] = b
                  print(a.size())
                  print(a)
                  

                  运行结果:

                  关于torch.topk, torch.max(),torch.argmax()

                  value, index = torch.topk(decoder_output_t , k = 1)
                  decoder_output_t [batch_size, vocab_size]

                  示例代码:

                  import torch
                   
                  a = torch.randn((3, 5))
                  print(a.size())
                  print(a)
                   
                  values, index = torch.topk(a, k=1)
                  print(values)
                  print(index)
                  print(index.size())
                   
                  values, index = torch.max(a, dim=-1)
                  print(values)
                  print(index)
                  print(index.size())
                   
                  index = torch.argmax(a, dim=-1)
                  print(index)
                  print(index.size())
                   
                  index = a.argmax(dim=-1)
                  print(index)
                  print(index.size())
                  

                  运行结果:

                  若使用teacher forcing ,将采用下次真实值作为下个time step的输入

                  # 注意unsqueeze 相当于浅拷贝,不会对原张量进行修改
                   decoder_input = target[:,t].unsqueeze(-1)
                   target 形状 [batch_size, seq_len]
                   decoder_input 要求形状[batch_size, 1]

                  示例代码:

                  import torch
                   
                  a = torch.randn((3, 5))
                  print(a.size())
                  print(a)
                   
                  b = a[:, 3]
                  print(b.size())
                  print(b)
                  c = b.unsqueeze(-1)
                  print(c.size())
                  print(c)

                  运行结果:

                  七、完成seq2seq的模型

                  seq2seq.py:

                  import torch
                  import torch.nn as nn
                   
                   
                  class Seq2Seq(nn.Module):
                      def __init__(self, encoder, decoder):
                          super(Seq2Seq, self).__init__()
                          self.encoder = encoder
                          self.decoder = decoder
                   
                      def forward(self, input, target, input_length, target_length):
                          encoder_outputs, encoder_hidden = self.encoder(input, input_length)
                          decoder_outputs, decoder_hidden = self.decoder(encoder_hidden, target, target_length)
                          return decoder_outputs, decoder_hidden
                   
                      def evaluation(self, inputs, input_length):
                          encoder_outputs, encoder_hidden = self.encoder(inputs, input_length)
                          decoded_sentence = self.decoder.evaluation(encoder_hidden)
                          return decoded_sentence
                  

                  八、完成训练逻辑

                  为了加速训练,可以考虑在gpu上运行,那么在我们自顶一个所以的tensor和model都需要转化为CUDA支持的类型。

                  当前的数据量为500多万条,在GTX1070(8G显存)上训练,大概需要90分一个epoch,耐心的等待吧

                  train.py:

                  import torch
                  import config
                  from torch import optim
                  import torch.nn as nn
                  from encode import Encoder
                  from decode import Decoder
                  from seq2seq import Seq2Seq
                  from dataset import data_loader as train_dataloader
                  from word_sequence import WordSequence
                   
                  encoder = Encoder()
                  decoder = Decoder()
                  model = Seq2Seq(encoder, decoder)
                   
                  # device在config文件中实现
                  model.to(config.device)
                   
                  print(model)
                   
                  model.load_state_dict(torch.load("model/seq2seq_model.pkl"))
                  optimizer = optim.Adam(model.parameters())
                  optimizer.load_state_dict(torch.load("model/seq2seq_optimizer.pkl"))
                  criterion = nn.NLLLoss(ignore_index=WordSequence.PAD, reduction="mean")
                   
                   
                  def get_loss(decoder_outputs, target):
                      target = target.view(-1)  # [batch_size*max_len]
                      decoder_outputs = decoder_outputs.view(config.batch_size * config.max_len, -1)
                      return criterion(decoder_outputs, target)
                   
                   
                  def train(epoch):
                      for idx, (input, target, input_length, target_len) in enumerate(train_dataloader):
                          input = input.to(config.device)
                          target = target.to(config.device)
                          input_length = input_length.to(config.device)
                          target_len = target_len.to(config.device)
                   
                          optimizer.zero_grad()
                          ##[seq_len,batch_size,vocab_size] [batch_size,seq_len]
                          decoder_outputs, decoder_hidden = model(input, target, input_length, target_len)
                          loss = get_loss(decoder_outputs, target)
                          loss.backward()
                          optimizer.step()
                   
                          print('Train Epoch: {} [{}/{} ({:.0f}%)]\tLoss: {:.6f}'.format(
                              epoch, idx * len(input), len(train_dataloader.dataset),
                                     100. * idx / len(train_dataloader), loss.item()))
                   
                          torch.save(model.state_dict(), "model/seq2seq_model.pkl")
                          torch.save(optimizer.state_dict(), 'model/seq2seq_optimizer.pkl')
                   
                   
                  if __name__ == '__main__':
                      for i in range(10):
                          train(i)
                  

                  训练10个epoch之后的效果如下,可以看出损失依然很高:

                  Train Epoch: 9 [2444544/4889919 (50%)]	Loss: 4.923604
                  Train Epoch: 9 [2444800/4889919 (50%)]	Loss: 4.364594
                  Train Epoch: 9 [2445056/4889919 (50%)]	Loss: 4.613254
                  Train Epoch: 9 [2445312/4889919 (50%)]	Loss: 4.143538
                  Train Epoch: 9 [2445568/4889919 (50%)]	Loss: 4.412729
                  Train Epoch: 9 [2445824/4889919 (50%)]	Loss: 4.516526
                  Train Epoch: 9 [2446080/4889919 (50%)]	Loss: 4.124945
                  Train Epoch: 9 [2446336/4889919 (50%)]	Loss: 4.777015
                  Train Epoch: 9 [2446592/4889919 (50%)]	Loss: 4.358538
                  Train Epoch: 9 [2446848/4889919 (50%)]	Loss: 4.513412
                  Train Epoch: 9 [2447104/4889919 (50%)]	Loss: 4.202757
                  Train Epoch: 9 [2447360/4889919 (50%)]	Loss: 4.589584
                  

                  九、评估逻辑

                  decoder 中添加评估方法

                  def evaluate(self, encoder_hidden):
                  	 """
                  	 评估, 和fowward逻辑类似
                  	 :param encoder_hidden: encoder最后time step的隐藏状态 [1, batch_size, hidden_size]
                  	 :return:
                  	 """
                  	 batch_size = encoder_hidden.size(1)
                  	 # 初始化一个[batch_size, 1]的SOS张量,作为第一个time step的输出
                  	 decoder_input = torch.LongTensor([[config.target_ws.SOS]] * batch_size).to(config.device)
                  	 # encoder_hidden 作为decoder第一个时间步的hidden [1, batch_size, hidden_size]
                  	 decoder_hidden = encoder_hidden
                  	 # 初始化[batch_size, seq_len, vocab_size]的outputs 拼接每个time step结果
                  	 decoder_outputs = torch.zeros((batch_size, config.chatbot_target_max_len, self.vocab_size)).to(config.device)
                  	 # 初始化一个空列表,存储每次的预测序列
                  	 predict_result = []
                  	 # 对每个时间步进行更新
                  	 for t in range(config.chatbot_target_max_len):
                  	     decoder_output_t, decoder_hidden = self.forward_step(decoder_input, decoder_hidden)
                  	     # 拼接每个time step,decoder_output_t [batch_size, vocab_size]
                  	     decoder_outputs[:, t, :] = decoder_output_t
                  	     # 由于是评估,需要每次都获取预测值
                  	     index = torch.argmax(decoder_output_t, dim = -1)
                  	     # 更新下一时间步的输入
                  	     decoder_input = index.unsqueeze(1)
                  	     # 存储每个时间步的预测序列
                  	     predict_result.append(index.cpu().detach().numpy()) # [[batch], [batch]...] ->[seq_len, vocab_size]
                  	 # 结果转换为ndarry,每行是一个预测结果即单个字对应的索引, 所有行为seq_len长度
                  	 predict_result = np.array(predict_result).transpose()  # (batch_size, seq_len)的array
                  	 return decoder_outputs, predict_result
                  

                  eval.py

                  import torch
                  import torch.nn as nn
                  import torch.nn.functional as F
                  from dataset import get_dataloader
                  import config
                  import numpy as np
                  from Seq2Seq import Seq2SeqModel
                  import os
                  from tqdm import tqdm
                   
                   
                   
                  model = Seq2SeqModel().to(config.device)
                  if os.path.exists('./model/chatbot_model.pkl'):
                      model.load_state_dict(torch.load('./model/chatbot_model.pkl'))
                   
                   
                  def eval():
                      model.eval()
                      loss_list = []
                      test_data_loader = get_dataloader(train = False)
                      with torch.no_grad():
                          bar = tqdm(test_data_loader, desc = 'testing', total = len(test_data_loader))
                          for idx, (input, target, input_length, target_length) in enumerate(bar):
                              input = input.to(config.device)
                              target = target.to(config.device)
                              input_length = input_length.to(config.device)
                              target_length = target_length.to(config.device)
                              # 获取模型的预测结果
                              decoder_outputs, predict_result = model.evaluation(input, input_length)
                              # 计算损失
                              loss = F.nll_loss(decoder_outputs.view(-1, len(config.target_ws)), target.view(-1), ignore_index = config.target_ws.PAD)
                              loss_list.append(loss.item())
                              bar.set_description('idx{}:/{}, loss:{}'.format(idx, len(test_data_loader), np.mean(loss_list)))
                   
                   
                  if __name__ == '__main__':
                      eval()
                  

                  interface.py:

                  from cut_sentence import cut
                  import torch
                  import config
                  from Seq2Seq import Seq2SeqModel
                  import os
                   
                   
                  # 模拟聊天场景,对用户输入进来的话进行回答
                  def interface():
                      # 加载训练集好的模型
                      model = Seq2SeqModel().to(config.device)
                      assert os.path.exists('./model/chatbot_model.pkl') , '请先对模型进行训练!'
                      model.load_state_dict(torch.load('./model/chatbot_model.pkl'))
                      model.eval()
                   
                      while True:
                          # 输入进来的原始字符串,进行分词处理
                          input_string = input('me>>:')
                          if input_string == 'q':
                              print('下次再聊')
                              break
                          input_cuted = cut(input_string, by_word = True)
                          # 进行序列转换和tensor封装
                          input_tensor = torch.LongTensor([config.input_ws.transfrom(input_cuted, max_len = config.chatbot_input_max_len)]).to(config.device)
                          input_length_tensor = torch.LongTensor([len(input_cuted)]).to(config.device)
                          # 获取预测结果
                          outputs, predict = model.evaluation(input_tensor, input_length_tensor)
                          # 进行序列转换文本
                          result = config.target_ws.inverse_transform(predict[0])
                          print('chatbot>>:', result)
                   
                   
                  if __name__ == '__main__':
                      interface()