模型訓練
模型加載和保存
模型調參流程
模型訓練:構造訓練集和驗證集,每輪進行訓練和驗證,並根據最優驗證集精度保存模型,代碼如下:
train_loader = torch.utils.data.DataLoader(
train_dataset,
batch_size=10,
shuffle=False,
num_workers=0,
)
val_loader = torch.utils.data.DataLoader(
val_dataset,
batch_size=10,
shuffle=False,
num_workers=0,
)
model = SVHN_Model1()
criterion = nn.CrossEntropyLoss (size_average=False)
optimizer = torch.optim.Adam(model.parameters(), 0.001)
best_loss = 1000.0
for epoch in range(20):
print('Epoch: ', epoch)
train(train_loader, model, criterion, optimizer, epoch)
val_loss = validate(val_loader, model, criterion)
# 記錄下驗證集精度
if val_loss < best_loss:
best_loss = val_loss
torch.save(model.state_dict(), './model.pt')
每個Epoch的訓練代碼:
def train(train_loader, model, criterion, optimizer, epoch):
# 切換模型爲訓練模式
model.train()
for i, (input, target) in enumerate(train_loader):
c0, c1, c2, c3, c4, c5 = model(data[0])
loss = criterion(c0, data[1][:, 0]) + \
criterion(c1, data[1][:, 1]) + \
criterion(c2, data[1][:, 2]) + \
criterion(c3, data[1][:, 3]) + \
criterion(c4, data[1][:, 4]) + \
criterion(c5, data[1][:, 5])
loss /= 6
optimizer.zero_grad()
loss.backward()
optimizer.step()
Epoch的驗證代碼:
def validate(val_loader, model, criterion):
# 切換模型爲預測模型
model.eval()
val_loss = []
# 不記錄模型梯度信息
with torch.no_grad():
for i, (input, target) in enumerate(val_loader):
c0, c1, c2, c3, c4, c5 = model(data[0])
loss = criterion(c0, data[1][:, 0]) + \
criterion(c1, data[1][:, 1]) + \
criterion(c2, data[1][:, 2]) + \
criterion(c3, data[1][:, 3]) + \
criterion(c4, data[1][:, 4]) + \
criterion(c5, data[1][:, 5])
loss /= 6
val_loss.append(loss.item())
return np.mean(val_loss)
模型加載和保存:
torch.save(model_object.state_dict(), ‘model.pt’)
model.load_state_dict(torch.load(’ model.pt’))
模型調參流程:
根據baseline的模型,跑通訓練、驗證和預測的流程;
簡單CNN模型的損失會比較大,嘗試增加模型複雜度,並觀察驗證集精度;如果精度太低,可以在增加模型複雜度的同時增加數據擴增方法,直至驗證集精度不變。