torch word2vec +bilstm 分类
时间: 2023-05-10 15:02:57 浏览: 219
Torch word2vec和bilstm分类是两个非常有用的深度学习工具。Torch word2vec是一种用于词向量嵌入的技术,它将每个单词转换为一个向量表示,并在向量空间中对它们进行编码。这使得它们在机器学习问题中非常有用,例如自然语言处理和文本分类。Torch word2vec可以通过将文本语料库传递给模型来训练,从而为每个单词生成一个向量。这些向量在大多数情况下是稠密的,即它们具有相对较少的元素,而且它们的分布是连续的,这使得它们易于在机器学习问题中使用。
相反,bilstm是一种用于分类的技术。它使用双向长短时记忆网络(bi-directional Long Short-Term Memory),这是一种特殊的循环神经网络,它可以处理和预测分布式数据,例如自然语言。bilstm是一种有监督机器学习算法,它可以通过训练样本来进行分类。训练样本是具有标签的文本数据,例如文章或评论,每个文本都对应一个标签。通过运行bilstm并向其传递文本,它可以预测每个文本对应的标签。这种技术在分类任务中非常有用,例如情感分析,推荐算法和主题分类等。
将这两种技术结合使用可以非常有效地解决自然语言处理问题。例如,将Torch word2vec用于生成单词向量,然后将这些向量传递给bilstm进行分类。通过将这两种技术结合使用,可以使用bilstm对文本数据进行分类,同时利用Torch word2vec生成的向量表示来增强模型。这种技术已经被广泛用于自然语言处理和文本分类中,并且已经被证明是一种非常强大和有效的机器学习技术。
相关问题
bilstm-crf代码
以下是一个简单的BiLSTM-CRF模型的PyTorch实现:
```python
import torch
import torch.nn as nn
class BiLSTM_CRF(nn.Module):
def __init__(self, vocab_size, tag_to_ix, embedding_dim, hidden_dim):
super(BiLSTM_CRF, self).__init__()
self.vocab_size = vocab_size
self.tag_to_ix = tag_to_ix
self.embedding_dim = embedding_dim
self.hidden_dim = hidden_dim
self.tagset_size = len(tag_to_ix)
self.word_embeds = nn.Embedding(vocab_size, embedding_dim)
self.lstm = nn.LSTM(embedding_dim, hidden_dim // 2, num_layers=1, bidirectional=True)
self.hidden2tag = nn.Linear(hidden_dim, self.tagset_size)
self.transitions = nn.Parameter(torch.randn(self.tagset_size, self.tagset_size))
self.transitions.data[tag_to_ix[START_TAG], :] = -10000
self.transitions.data[:, tag_to_ix[STOP_TAG]] = -10000
def _forward_alg(self, feats):
init_alphas = torch.full((1, self.tagset_size), -10000.)
init_alphas[0][self.tag_to_ix[START_TAG]] = 0.
forward_var = init_alphas
for feat in feats:
alphas_t = []
for next_tag in range(self.tagset_size):
emit_score = feat[next_tag].view(1, -1).expand(1, self.tagset_size)
trans_score = self.transitions[next_tag].view(1, -1)
next_tag_var = forward_var + trans_score + emit_score
alphas_t.append(log_sum_exp(next_tag_var).view(1))
forward_var = torch.cat(alphas_t).view(1, -1)
terminal_var = forward_var + self.transitions[self.tag_to_ix[STOP_TAG]]
alpha = log_sum_exp(terminal_var)
return alpha
def _score_sentence(self, feats, tags):
score = torch.zeros(1)
tags = torch.cat([torch.tensor([self.tag_to_ix[START_TAG]], dtype=torch.long), tags])
for i, feat in enumerate(feats):
score = score + \
self.transitions[tags[i + 1], tags[i]] + feat[tags[i + 1]]
score = score + self.transitions[self.tag_to_ix[STOP_TAG], tags[-1]]
return score
def _viterbi_decode(self, feats):
backpointers = []
init_vvars = torch.full((1, self.tagset_size), -10000.)
init_vvars[0][self.tag_to_ix[START_TAG]] = 0
forward_var = init_vvars
for feat in feats:
bptrs_t = []
viterbivars_t = []
for next_tag in range(self.tagset_size):
next_tag_var = forward_var + self.transitions[next_tag]
best_tag_id = argmax(next_tag_var)
bptrs_t.append(best_tag_id)
viterbivars_t.append(next_tag_var[0][best_tag_id].view(1))
forward_var = (torch.cat(viterbivars_t) + feat).view(1, -1)
backpointers.append(bptrs_t)
terminal_var = forward_var + self.transitions[self.tag_to_ix[STOP_TAG]]
best_tag_id = argmax(terminal_var)
path_score = terminal_var[0][best_tag_id]
best_path = [best_tag_id]
for bptrs_t in reversed(backpointers):
best_tag_id = bptrs_t[best_tag_id]
best_path.append(best_tag_id)
start = best_path.pop()
assert start == self.tag_to_ix[START_TAG]
best_path.reverse()
return path_score, best_path
def forward(self, sentence):
lstm_feats = self._get_lstm_features(sentence)
score, tag_seq = self._viterbi_decode(lstm_feats)
return score, tag_seq
def _get_lstm_features(self, sentence):
self.hidden = self.init_hidden()
embeds = self.word_embeds(sentence).view(len(sentence), 1, -1)
lstm_out, self.hidden = self.lstm(embeds, self.hidden)
lstm_out = lstm_out.view(len(sentence), self.hidden_dim)
lstm_feats = self.hidden2tag(lstm_out)
return lstm_feats
def neg_log_likelihood(self, sentence, tags):
lstm_feats = self._get_lstm_features(sentence)
forward_score = self._forward_alg(lstm_feats)
gold_score = self._score_sentence(lstm_feats, tags)
return forward_score - gold_score
def init_hidden(self):
return (torch.randn(2, 1, self.hidden_dim // 2),
torch.randn(2, 1, self.hidden_dim // 2))
def log_sum_exp(vec):
max_score = vec[0, argmax(vec)]
max_score_broadcast = max_score.view(1, -1).expand(1, vec.size()[1])
return max_score + \
torch.log(torch.sum(torch.exp(vec - max_score_broadcast)))
def argmax(vec):
_, idx = torch.max(vec, 1)
return idx.item()
```
其中,`START_TAG`和`STOP_TAG`是起始标记和结束标记。这里使用了`log_sum_exp`函数来处理数值上溢的问题,`argmax`函数用于取最大值的下标。这个模型可以用于序列标注任务,例如词性标注、命名实体识别等。
BiLSTM-CRF如何使用
BiLSTM-CRF是一种常用的命名实体识别方法,其使用双向LSTM进行特征提取,再使用CRF进行标注。具体步骤如下:
1.准备数据集,将文本中的实体标注出来,例如人名、地名、组织机构名等。
2.将文本转化为数字表示,例如使用词向量将每个词转化为向量。
3.使用BiLSTM对输入的词向量进行特征提取,得到每个词的特征向量。
4.将BiLSTM的输出作为CRF的输入,使用CRF进行标注,得到每个词的标签。
5.根据标签将文本中的实体识别出来。
以下是一个简单的BiLSTM-CRF的实现代码:
```python
import torch
import torch.nn as nn
import torch.optim as optim
class BiLSTM_CRF(nn.Module):
def __init__(self, vocab_size, tag_to_ix, embedding_dim, hidden_dim):
super(BiLSTM_CRF, self).__init__()
self.embedding_dim = embedding_dim
self.hidden_dim = hidden_dim
self.vocab_size = vocab_size
self.tag_to_ix = tag_to_ix
self.tagset_size = len(tag_to_ix)
self.word_embeds = nn.Embedding(vocab_size, embedding_dim)
self.lstm = nn.LSTM(embedding_dim, hidden_dim // 2,
num_layers=1, bidirectional=True)
self.hidden2tag = nn.Linear(hidden_dim, self.tagset_size)
self.transitions = nn.Parameter(
torch.randn(self.tagset_size, self.tagset_size))
self.transitions.data[tag_to_ix['START_TAG'], :] = -10000
self.transitions.data[:, tag_to_ix['STOP_TAG']] = -10000
self.hidden = self.init_hidden()
def init_hidden(self):
return (torch.randn(2, 1, self.hidden_dim // 2),
torch.randn(2, 1, self.hidden_dim // 2))
def _forward_alg(self, feats):
init_alphas = torch.full((1, self.tagset_size), -10000.)
init_alphas[0][self.tag_to_ix['START_TAG']] = 0.
forward_var = init_alphas
for feat in feats:
alphas_t = []
for next_tag in range(self.tagset_size):
emit_score = feat[next_tag].view(
1, -1).expand(1, self.tagset_size)
trans_score = self.transitions[next_tag].view(1, -1)
next_tag_var = forward_var + trans_score + emit_score
alphas_t.append(self._log_sum_exp(next_tag_var).view(1))
forward_var = torch.cat(alphas_t).view(1, -1)
terminal_var = forward_var + self.transitions[self.tag_to_ix['STOP_TAG']]
alpha = self._log_sum_exp(terminal_var)
return alpha
def _score_sentence(self, feats, tags):
score = torch.zeros(1)
tags = torch.cat([torch.tensor([self.tag_to_ix['START_TAG']], dtype=torch.long), tags])
for i, feat in enumerate(feats):
score = score + \
self.transitions[tags[i + 1], tags[i]] + feat[tags[i + 1]]
score = score + self.transitions[self.tag_to_ix['STOP_TAG'], tags[-1]]
return score
def _viterbi_decode(self, feats):
backpointers = []
init_vvars = torch.full((1, self.tagset_size), -10000.)
init_vvars[0][self.tag_to_ix['START_TAG']] = 0
forward_var = init_vvars
for feat in feats:
bptrs_t = []
viterbivars_t = []
for next_tag in range(self.tagset_size):
next_tag_var = forward_var + self.transitions[next_tag]
best_tag_id = self._argmax(next_tag_var)
bptrs_t.append(best_tag_id)
viterbivars_t.append(next_tag_var[0][best_tag_id].view(1))
forward_var = (torch.cat(viterbivars_t) + feat).view(1, -1)
backpointers.append(bptrs_t)
terminal_var = forward_var + self.transitions[self.tag_to_ix['STOP_TAG']]
best_tag_id = self._argmax(terminal_var)
path_score = terminal_var[0][best_tag_id]
best_path = [best_tag_id]
for bptrs_t in reversed(backpointers):
best_tag_id = bptrs_t[best_tag_id]
best_path.append(best_tag_id)
start = best_path.pop()
assert start == self.tag_to_ix['START_TAG']
best_path.reverse()
return path_score, best_path
def _log_sum_exp(self, vec):
max_score = vec[0, self._argmax(vec)]
max_score_broadcast = max_score.view(1, -1).expand(1, vec.size()[1])
return max_score + \
torch.log(torch.sum(torch.exp(vec - max_score_broadcast)))
def _argmax(self, vec):
_, idx = torch.max(vec, 1)
return idx.item()
def neg_log_likelihood(self, sentence, tags):
self.hidden = self.init_hidden()
embeds = self.word_embeds(sentence).view(len(sentence), 1, -1)
lstm_out, self.hidden = self.lstm(embeds, self.hidden)
lstm_out = lstm_out.view(len(sentence), self.hidden_dim)
tag_scores = self.hidden2tag(lstm_out)
forward_score = self._forward_alg(tag_scores)
gold_score = self._score_sentence(tag_scores, tags)
return forward_score - gold_score
def forward(self, sentence):
self.hidden = self.init_hidden()
embeds = self.word_embeds(sentence).view(len(sentence), 1, -1)
lstm_out, self.hidden = self.lstm(embeds, self.hidden)
lstm_out = lstm_out.view(len(sentence), self.hidden_dim)
tag_scores = self.hidden2tag(lstm_out)
score, tag_seq = self._viterbi_decode(tag_scores)
return score, tag_seq
```
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