Python PyTorch SequentialLR用法及代碼示例

本文簡要介紹python語言中 torch.optim.lr_scheduler.SequentialLR 的用法。

用法:

class torch.optim.lr_scheduler.SequentialLR(optimizer, schedulers, milestones, last_epoch=- 1, verbose=False)

參數：

• schedulers(list) -鏈式調度程序列表。

• milestones(list) -反映裏程碑點的整數列表。

接收預計在優化過程中按順序調用的調度程序列表和提供準確間隔以反映在給定時期應該調用哪個調度程序的裏程碑點。

示例

>>> # Assuming optimizer uses lr = 1. for all groups
>>> # lr = 0.1     if epoch == 0
>>> # lr = 0.1     if epoch == 1
>>> # lr = 0.9     if epoch == 2
>>> # lr = 0.81    if epoch == 3
>>> # lr = 0.729   if epoch == 4
>>> scheduler1 = ConstantLR(self.opt, factor=0.1, total_iters=2)
>>> scheduler2 = ExponentialLR(self.opt, gamma=0.9)
>>> scheduler = SequentialLR(self.opt, schedulers=[scheduler1, scheduler2], milestones=[2])
>>> for epoch in range(100):
>>>     train(...)
>>>     validate(...)
>>>     scheduler.step()