请给我一个简单的，仅用pytorch和pycharm的encoder-decoder模型代码

好的，以下是一个简单的encoder-decoder模型的代码，仅使用PyTorch和PyCharm：

import torch
import torch.nn as nn
import torch.optim as optim

# 定义 Encoder 模型
class Encoder(nn.Module):

    def __init__(self, input_size, hidden_size):
        super(Encoder, self).__init__()
        self.hidden_size = hidden_size

        self.embedding = nn.Embedding(input_size, hidden_size)
        self.gru = nn.GRU(hidden_size, hidden_size)

    def forward(self, input, hidden):
        embedded = self.embedding(input).view(1, 1, -1)
        output = embedded
        output, hidden = self.gru(output, hidden)
        return output, hidden

    def init_hidden(self):
        return torch.zeros(1, 1, self.hidden_size)


# 定义 Decoder 模型
class Decoder(nn.Module):

    def __init__(self, hidden_size, output_size):
        super(Decoder, self).__init__()
        self.hidden_size = hidden_size

        self.embedding = nn.Embedding(output_size, hidden_size)
        self.gru = nn.GRU(hidden_size, hidden_size)
        self.out = nn.Linear(hidden_size, output_size)
        self.softmax = nn.LogSoftmax(dim=1)

    def forward(self, input, hidden):
        output = self.embedding(input).view(1, 1, -1)
        output = nn.functional.relu(output)
        output, hidden = self.gru(output, hidden)
        output = self.softmax(self.out(output[0]))
        return output, hidden

    def init_hidden(self):
        return torch.zeros(1, 1, self.hidden_size)


# 定义训练函数
def train(input_tensor, target_tensor, encoder, decoder, encoder_optimizer, decoder_optimizer, criterion, max_length=20):
    encoder_hidden = encoder.init_hidden()

    encoder_optimizer.zero_grad()
    decoder_optimizer.zero_grad()

    input_length = input_tensor.size(0)
    target_length = target_tensor.size(0)

    encoder_outputs = torch.zeros(max_length, encoder.hidden_size, device=device)

    loss = 0

    for ei in range(input_length):
        encoder_output, encoder_hidden = encoder(
            input_tensor[ei], encoder_hidden)
        encoder_outputs[ei] = encoder_output[0, 0]

    decoder_input = torch.tensor([[SOS_token]], device=device)

    decoder_hidden = encoder_hidden

    for di in range(target_length):
        decoder_output, decoder_hidden = decoder(
            decoder_input, decoder_hidden)
        loss += criterion(decoder_output, target_tensor[di])
        decoder_input = target_tensor[di]  

    loss.backward()

    encoder_optimizer.step()
    decoder_optimizer.step()

    return loss.item() / target_length


# 定义翻译函数
def evaluate(encoder, decoder, sentence, max_length=20):
    with torch.no_grad():
        input_tensor = tensorFromSentence(input_lang, sentence)
        input_length = input_tensor.size()[0]
        encoder_hidden = encoder.init_hidden()

        encoder_outputs = torch.zeros(max_length, encoder.hidden_size, device=device)

        for ei in range(input_length):
            encoder_output, encoder_hidden = encoder(input_tensor[ei],
                                                     encoder_hidden)
            encoder_outputs[ei] += encoder_output[0, 0]

        decoder_input = torch.tensor([[SOS_token]], device=device)
        decoder_hidden = encoder_hidden

        decoded_words = []
        for di in range(max_length):
            decoder_output, decoder_hidden = decoder(
                decoder_input, decoder_hidden)
            topv, topi = decoder_output.data.topk(1)
            if topi.item() == EOS_token:
                decoded_words.append('<EOS>')
                break
            else:
                decoded_words.append(output_lang.index2word[topi.item()])

            decoder_input = topi.squeeze().detach()

        return decoded_words


# 主程序
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")

input_lang, output_lang, pairs = prepareData('eng', 'fra', True)
print(random.choice(pairs))

hidden_size = 256
encoder1 = Encoder(input_lang.n_words, hidden_size).to(device)
decoder1 = Decoder(hidden_size, output_lang.n_words).to(device)

learning_rate = 0.01
encoder_optimizer = optim.SGD(encoder1.parameters(), lr=learning_rate)
decoder_optimizer = optim.SGD(decoder1.parameters(), lr=learning_rate)

criterion = nn.NLLLoss()

n_iters = 10000
print_every = 1000
plot_every = 1000

training_pairs = [tensorsFromPair(random.choice(pairs))
                  for i in range(n_iters)]
losses = []

for iter in range(1, n_iters + 1):
    training_pair = training_pairs[iter - 1]
    input_tensor = training_pair[0]
    target_tensor = training_pair[1]

    loss = train(input_tensor, target_tensor, encoder1,
                 decoder1, encoder_optimizer, decoder_optimizer, criterion)
    losses.append(loss)

    if iter % print_every == 0:
        print('(%d %d%%) %.4f' % (iter, iter / n_iters * 100, loss))

这个代码实现了一个简单的英法翻译的encoder-decoder模型，使用了PyTorch和PyCharm。不过需要注意的是，这个代码使用了一些其他的函数和数据，需要自行调整和补充。