pytorch 双向LSTM

PyTorch中双向LSTM模型可以使用torch.nn中的nn.LSTM模块，并设置参数bidirectional=True。例如：

import torch.nn as nn

class BiLSTM(nn.Module):
    def __init__(self, input_dim, hidden_dim, num_layers, output_dim):
        super(BiLSTM, self).__init__()
        self.hidden_dim = hidden_dim
        self.num_layers = num_layers
        self.lstm = nn.LSTM(input_dim, hidden_dim, num_layers, batch_first=True, bidirectional=True)
        self.fc = nn.Linear(hidden_dim*2, output_dim)

    def forward(self, x):
        h0 = torch.zeros(self.num_layers*2, x.size(0), self.hidden_dim).to(device)
        c0 = torch.zeros(self.num_layers*2, x.size(0), self.hidden_dim).to(device)

        out, (hidden_state, cell_state) = self.lstm(x, (h0, c0))
        # 将双向LSTM的输出沿最后一维拼接
        final_hidden_state = torch.cat((hidden_state[-2,:,:], hidden_state[-1,:,:]), dim=1)
        out = self.fc(final_hidden_state)

        return out