在MAGNet中使用回調(diào)函數(shù)可以通過自定義回調(diào)函數(shù)類來實(shí)現(xiàn)。下面是一個簡單的示例代碼,展示如何在MAGNet中使用回調(diào)函數(shù)監(jiān)控訓(xùn)練過程:
import torch
import ignite
from ignite.engine import Events, create_supervised_trainer, create_supervised_evaluator
from ignite.metrics import Loss
class CustomCallback:
def __init__(self):
self.metrics = {
'loss': Loss(torch.nn.CrossEntropyLoss())
}
def attach(self, engine):
for name, metric in self.metrics.items():
metric.attach(engine, name)
def update(self, engine, batch):
inputs, targets = batch
outputs = engine.state.model(inputs)
loss = engine.state.criterion(outputs, targets)
return loss, outputs, targets
def on_iteration_completed(self, engine):
for name, metric in self.metrics.items():
metric.update(engine.state.output)
def on_epoch_completed(self, engine):
for name, metric in self.metrics.items():
print(f'{name}: {metric.compute()}')
train_loader = torch.utils.data.DataLoader(dataset, batch_size=batch_size, shuffle=True)
model = MyModel()
optimizer = torch.optim.Adam(model.parameters(), lr=0.001)
criterion = torch.nn.CrossEntropyLoss()
trainer = create_supervised_trainer(model, optimizer, criterion)
evaluator = create_supervised_evaluator(model, metrics={'accuracy': Accuracy()})
callback = CustomCallback()
callback.attach(trainer)
@trainer.on(Events.ITERATION_COMPLETED)
def log_training_loss(engine):
callback.on_iteration_completed(engine)
@trainer.on(Events.EPOCH_COMPLETED)
def log_epoch_metrics(engine):
callback.on_epoch_completed(engine)
trainer.run(train_loader, max_epochs=num_epochs)
在這個示例代碼中,我們定義了一個名為CustomCallback的類來管理監(jiān)控訓(xùn)練過程的邏輯。我們創(chuàng)建了一個trainer引擎,并在每個iteration結(jié)束和每個epoch結(jié)束時調(diào)用CustomCallback中定義的方法來更新監(jiān)控指標(biāo)并打印結(jié)果。
需要注意的是,ignite提供了許多預(yù)定義的事件(Events),可以用來注冊回調(diào)函數(shù)來監(jiān)控訓(xùn)練過程中的不同階段。在這個示例中,我們注冊了ITERATION_COMPLETED和EPOCH_COMPLETED兩個事件,分別在每個iteration和每個epoch結(jié)束時調(diào)用相應(yīng)的回調(diào)函數(shù)。
通過自定義回調(diào)函數(shù)類和注冊回調(diào)函數(shù)來監(jiān)控訓(xùn)練過程,我們可以靈活地在MAGNet中實(shí)現(xiàn)監(jiān)控邏輯,方便地獲取訓(xùn)練過程中的指標(biāo)和結(jié)果。