PyTorch - How to get learning rate during training?
While training, I'd like to know the value of learning_rate.
What should I do?

It's my code, like this:

my_optimizer = torch.optim.SGD(my_model.parameters(), 
                               lr=0.001, 
                               momentum=0.99, 
                               weight_decay=2e-3)


Thank you.

For only one parameter group like in the example you've given, you can use this function and call it during training to get the current learning rate:

def get_lr(optimizer):
    for param_group in optimizer.param_groups:
        return param_group['lr']

