for batch_id, data in enumerate(train_loader()):改为torch代码
时间: 2024-01-25 11:03:27 浏览: 35
以下是将 `train_loader()` 改为 `train_loader` 的 PyTorch 代码:
```
for batch_id, data in enumerate(train_loader):
# do something with data
```
在 PyTorch 中,`DataLoader` 对象不需要使用括号 `()` 进行调用。你可以像迭代列表一样迭代 `DataLoader` 对象来获取数据集的批次。
相关问题
for _step, input_data in enumerate(train_loader): 而train_loader = torch.utils.data.DataLoader(train_dataset, batch_size=64, shuffle=True, num_workers=0),会循环多少次
根据代码中提供的信息,train_loader 是一个 DataLoader 对象,其参数 batch_size 为 64,shuffle 为 True,num_workers 为 0,即使用当前进程加载数据。因此,train_loader 每次会将 train_dataset 中的 64 个样本打包成一个 batch,并且随机打乱样本顺序。如果 train_dataset 中的样本数量不足 64 个,那么 train_loader 最后几个 batch 的大小会小于 64。由于在循环中使用了 enumerate 函数,因此 _step 会记录当前循环的次数,即 train_loader 会循环 train_dataset 中的所有样本,直到遍历完整个数据集为止。因此,train_loader 会循环的次数为 train_dataset 中样本数量除以 batch_size 的上取整值,即 ceil(len(train_dataset) / batch_size)。
检查一下:import torch import torch.nn as nn import torch.optim as optim from torch.utils.data import DataLoader, TensorDataset from sklearn.metrics import roc_auc_score # 定义神经网络模型 class Net(nn.Module): def __init__(self): super(Net, self).__init__() self.fc1 = nn.Linear(10, 64) self.fc2 = nn.Linear(64, 32) self.fc3 = nn.Linear(32, 1) self.sigmoid = nn.Sigmoid() def forward(self, x): x = self.fc1(x) x = nn.functional.relu(x) x = self.fc2(x) x = nn.functional.relu(x) x = self.fc3(x) x = self.sigmoid(x) return x # 加载数据集 data = torch.load('data.pt') x_train, y_train, x_test, y_test = data train_dataset = TensorDataset(x_train, y_train) train_loader = DataLoader(train_dataset, batch_size=32, shuffle=True) test_dataset = TensorDataset(x_test, y_test) test_loader = DataLoader(test_dataset, batch_size=32, shuffle=False) # 定义损失函数和优化器 criterion = nn.BCELoss() optimizer = optim.Adam(net.parameters(), lr=0.01) # 训练模型 net = Net() for epoch in range(10): running_loss = 0.0 for i, data in enumerate(train_loader): inputs, labels = data optimizer.zero_grad() outputs = net(inputs) loss = criterion(outputs, labels) loss.backward() optimizer.step() running_loss += loss.item() # 在测试集上计算AUC y_pred = [] y_true = [] with torch.no_grad(): for data in test_loader: inputs, labels = data outputs = net(inputs) y_pred += outputs.tolist() y_true += labels.tolist() auc = roc_auc_score(y_true, y_pred) print('Epoch %d, loss: %.3f, test AUC: %.3f' % (epoch + 1, running_loss / len(train_loader), auc))
在运行代码之前,需要将 `net = Net()` 放在 `optimizer = optim.Adam(net.parameters(), lr=0.01)` 的前面,因为在定义优化器时需要先传入模型的参数。另外,代码中没有定义 `net`,需要先将 `Net` 类定义好再进行实例化。正确的代码如下所示:
```python
import torch
import torch.nn as nn
import torch.optim as optim
from torch.utils.data import DataLoader, TensorDataset
from sklearn.metrics import roc_auc_score
# 定义神经网络模型
class Net(nn.Module):
def __init__(self):
super(Net, self).__init__()
self.fc1 = nn.Linear(10, 64)
self.fc2 = nn.Linear(64, 32)
self.fc3 = nn.Linear(32, 1)
self.sigmoid = nn.Sigmoid()
def forward(self, x):
x = self.fc1(x)
x = nn.functional.relu(x)
x = self.fc2(x)
x = nn.functional.relu(x)
x = self.fc3(x)
x = self.sigmoid(x)
return x
# 加载数据集
data = torch.load('data.pt')
x_train, y_train, x_test, y_test = data
train_dataset = TensorDataset(x_train, y_train)
train_loader = DataLoader(train_dataset, batch_size=32, shuffle=True)
test_dataset = TensorDataset(x_test, y_test)
test_loader = DataLoader(test_dataset, batch_size=32, shuffle=False)
# 定义损失函数和优化器
criterion = nn.BCELoss()
net = Net()
optimizer = optim.Adam(net.parameters(), lr=0.01)
# 训练模型
for epoch in range(10):
running_loss = 0.0
for i, data in enumerate(train_loader):
inputs, labels = data
optimizer.zero_grad()
outputs = net(inputs)
loss = criterion(outputs, labels)
loss.backward()
optimizer.step()
running_loss += loss.item()
# 在测试集上计算AUC
y_pred = []
y_true = []
with torch.no_grad():
for data in test_loader:
inputs, labels = data
outputs = net(inputs)
y_pred += outputs.tolist()
y_true += labels.tolist()
auc = roc_auc_score(y_true, y_pred)
print('Epoch %d, loss: %.3f, test AUC: %.3f' % (epoch + 1, running_loss / len(train_loader), auc))
```