请问下下面的batch_id是什么意思?在for循环里, batch_id和data是同时变化么?
for epoch in range(EPOCH_NUM):
for batch_id, data in enumerate(train_loader()):
images = norm_img(data[0]).astype('float32')
labels = data[1].astype('float32')
#前向计算的过程
predicts = model(images)
# 计算损失
loss = F.square_error_cost(predicts, labels)
avg_loss = paddle.mean(loss)
#每训练了1000批次的数据,打印下当前Loss的情况
if batch_id % 1000 == 0:
print("epoch_id: {}, batch_id: {}, loss is: {}".format(epoch, batch_id, avg_loss.numpy()))
#后向传播,更新参数的过程
avg_loss.backward()
opt.step()
opt.clear_grad()