将下面代码中的损失函数改成单类识别的损失函数:loss_function = torch.nn.CrossEntropyLoss() optimizer = optim.SGD( net.parameters(), lr=0.001, momentum=0.9
时间: 2024-05-26 11:10:36 浏览: 16
可以将损失函数改为torch.nn.BCEWithLogitsLoss(),同时需要将模型的输出改为一个标量,表示属于该类的概率。代码示例如下:
loss_function = torch.nn.BCEWithLogitsLoss()
optimizer = optim.SGD(net.parameters(), lr=0.001, momentum=0.9)
output = net(input)
loss = loss_function(output, target)
相关问题
model = CBOW(word_size, EMDEDDING_DIM) loss_function = nn.NLLLoss() optimizer = torch.optim.SGD(model.parameters(), lr=0.001) #开始训练 for epoch in range(100): total_loss = 0 for context, target in data: context_vector = make_context_vector(context, word_to_ix) log_probs = model(context_vector) total_loss += loss_function(log_probs, torch.tensor([word_to_ix[target]])) optimizer.zero_grad() total_loss.backward() optimizer.step()
这段代码展示了一个 CBOW(Continuous Bag-of-Words)模型的训练过程。首先,通过实例化 CBOW 模型来创建一个模型对象,其中 word_size 是词汇表的大小,EMBEDDING_DIM 是嵌入维度。然后,定义损失函数为负对数似然损失函数(NLLLoss)。接着,创建一个优化器对象,使用随机梯度下降(SGD)算法来更新模型参数,学习率为 0.001。
接下来是训练过程。代码中使用了一个嵌套的循环结构,外层循环控制训练的轮数,内层循环遍历训练数据集中的每个样本。在内层循环中,首先通过 make_context_vector 函数将上下文转换为张量形式(通过 word_to_ix 字典将单词映射为索引),然后将上下文张量作为输入传递给 CBOW 模型,得到预测的目标单词的对数概率。接着计算预测结果与真实目标之间的损失,并累加到 total_loss 中。
在每个样本处理完成后,调用 optimizer.zero_grad() 将梯度置零,然后调用 total_loss.backward() 计算损失对模型参数的梯度,并调用 optimizer.step() 更新模型参数。
重复上述过程,直到完成指定的训练轮数。通过不断迭代优化模型参数,使得模型能够预测目标单词的概率分布接近真实分布,从而实现词嵌入的训练。
下面的这段python代码,哪里有错误,修改一下:import numpy as np import matplotlib.pyplot as plt import pandas as pd import torch import torch.nn as nn from torch.autograd import Variable from sklearn.preprocessing import MinMaxScaler training_set = pd.read_csv('CX2-36_1971.csv') training_set = training_set.iloc[:, 1:2].values def sliding_windows(data, seq_length): x = [] y = [] for i in range(len(data) - seq_length): _x = data[i:(i + seq_length)] _y = data[i + seq_length] x.append(_x) y.append(_y) return np.array(x), np.array(y) sc = MinMaxScaler() training_data = sc.fit_transform(training_set) seq_length = 1 x, y = sliding_windows(training_data, seq_length) train_size = int(len(y) * 0.8) test_size = len(y) - train_size dataX = Variable(torch.Tensor(np.array(x))) dataY = Variable(torch.Tensor(np.array(y))) trainX = Variable(torch.Tensor(np.array(x[1:train_size]))) trainY = Variable(torch.Tensor(np.array(y[1:train_size]))) testX = Variable(torch.Tensor(np.array(x[train_size:len(x)]))) testY = Variable(torch.Tensor(np.array(y[train_size:len(y)]))) class LSTM(nn.Module): def __init__(self, num_classes, input_size, hidden_size, num_layers): super(LSTM, self).__init__() self.num_classes = num_classes self.num_layers = num_layers self.input_size = input_size self.hidden_size = hidden_size self.seq_length = seq_length self.lstm = nn.LSTM(input_size=input_size, hidden_size=hidden_size, num_layers=num_layers, batch_first=True) self.fc = nn.Linear(hidden_size, num_classes) def forward(self, x): h_0 = Variable(torch.zeros( self.num_layers, x.size(0), self.hidden_size)) c_0 = Variable(torch.zeros( self.num_layers, x.size(0), self.hidden_size)) # Propagate input through LSTM ula, (h_out, _) = self.lstm(x, (h_0, c_0)) h_out = h_out.view(-1, self.hidden_size) out = self.fc(h_out) return out num_epochs = 2000 learning_rate = 0.001 input_size = 1 hidden_size = 2 num_layers = 1 num_classes = 1 lstm = LSTM(num_classes, input_size, hidden_size, num_layers) criterion = torch.nn.MSELoss() # mean-squared error for regression optimizer = torch.optim.Adam(lstm.parameters(), lr=learning_rate) # optimizer = torch.optim.SGD(lstm.parameters(), lr=learning_rate) runn = 10 Y_predict = np.zeros((runn, len(dataY))) # Train the model for i in range(runn): print('Run: ' + str(i + 1)) for epoch in range(num_epochs): outputs = lstm(trainX) optimizer.zero_grad() # obtain the loss function loss = criterion(outputs, trainY) loss.backward() optimizer.step() if epoch % 100 == 0: print("Epoch: %d, loss: %1.5f" % (epoch, loss.item())) lstm.eval() train_predict = lstm(dataX) data_predict = train_predict.data.numpy() dataY_plot = dataY.data.numpy() data_predict = sc.inverse_transform(data_predict) dataY_plot = sc.inverse_transform(dataY_plot) Y_predict[i,:] = np.transpose(np.array(data_predict)) Y_Predict = np.mean(np.array(Y_predict)) Y_Predict_T = np.transpose(np.array(Y_Predict))
在这段代码中,可能存在以下错误:
1. 缺少必要的库或模块。
2. training_set 的文件路径是否正确。
3. training_set 的数据处理是否正确。
4. LSTM 模型的定义是否正确。
5. 训练和预测的代码是否正确。
下面是修改后的代码:
```python
import numpy as np
import matplotlib.pyplot as plt
import pandas as pd
import torch
import torch.nn as nn
from torch.autograd import Variable
from sklearn.preprocessing import MinMaxScaler
# 读取数据
training_set = pd.read_csv('CX2-36_1971.csv')
training_set = training_set.iloc[:, 1:2].values
# 定义数据处理函数
def sliding_windows(data, seq_length):
x = []
y = []
for i in range(len(data) - seq_length):
_x = data[i:(i + seq_length)]
_y = data[i + seq_length]
x.append(_x)
y.append(_y)
return np.array(x), np.array(y)
# 对数据进行归一化处理
sc = MinMaxScaler()
training_data = sc.fit_transform(training_set)
# 定义窗口长度
seq_length = 1
# 对数据进行窗口划分
x, y = sliding_windows(training_data, seq_length)
# 划分训练集和测试集
train_size = int(len(y) * 0.8)
test_size = len(y) - train_size
dataX = Variable(torch.Tensor(np.array(x)))
dataY = Variable(torch.Tensor(np.array(y)))
trainX = Variable(torch.Tensor(np.array(x[1:train_size])))
trainY = Variable(torch.Tensor(np.array(y[1:train_size])))
testX = Variable(torch.Tensor(np.array(x[train_size:len(x)])))
testY = Variable(torch.Tensor(np.array(y[train_size:len(y)])))
# 定义 LSTM 模型
class LSTM(nn.Module):
def __init__(self, num_classes, input_size, hidden_size, num_layers):
super(LSTM, self).__init__()
self.num_classes = num_classes
self.num_layers = num_layers
self.input_size = input_size
self.hidden_size = hidden_size
self.seq_length = seq_length
self.lstm = nn.LSTM(input_size=input_size, hidden_size=hidden_size,
num_layers=num_layers, batch_first=True)
self.fc = nn.Linear(hidden_size, num_classes)
def forward(self, x):
h_0 = Variable(torch.zeros(
self.num_layers, x.size(0), self.hidden_size))
c_0 = Variable(torch.zeros(
self.num_layers, x.size(0), self.hidden_size))
# Propagate input through LSTM
ula, (h_out, _) = self.lstm(x, (h_0, c_0))
h_out = h_out.view(-1, self.hidden_size)
out = self.fc(h_out)
return out
# 定义训练参数
num_epochs = 2000
learning_rate = 0.001
input_size = 1
hidden_size = 2
num_layers = 1
num_classes = 1
# 实例化 LSTM 模型
lstm = LSTM(num_classes, input_size, hidden_size, num_layers)
# 定义损失函数和优化器
criterion = torch.nn.MSELoss()
optimizer = torch.optim.Adam(lstm.parameters(), lr=learning_rate)
# 训练模型
runn = 10
Y_predict = np.zeros((runn, len(dataY)))
for i in range(runn):
print('Run: ' + str(i + 1))
for epoch in range(num_epochs):
outputs = lstm(trainX)
optimizer.zero_grad()
loss = criterion(outputs, trainY)
loss.backward()
optimizer.step()
if epoch % 100 == 0:
print("Epoch: %d, loss: %1.5f" % (epoch, loss.item()))
lstm.eval()
train_predict = lstm(dataX)
data_predict = train_predict.data.numpy()
dataY_plot = dataY.data.numpy()
# 对结果进行反归一化
data_predict = sc.inverse_transform(data_predict)
dataY_plot = sc.inverse_transform(dataY_plot)
Y_predict[i,:] = np.transpose(np.array(data_predict))
Y_Predict = np.mean(Y_predict, axis=0)
Y_Predict_T = np.transpose(np.array(Y_Predict))
```
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