from torch.optim.lr_scheduler import LRScheduler | |
class InterpolatingLogScheduler(LRScheduler): | |
def __init__(self, optimizer, num_steps, min_lr, max_lr, last_epoch=-1): | |
"""A scheduler that interpolates learning rates in a logarithmic fashion | |
Args: | |
- optimizer: pytorch optimizer | |
- num_steps: int, the number of steps over which to increase from the min_lr to the max_lr | |
- min_lr: float, the minimum learning rate | |
- max_lr: float, the maximum learning rate | |
Usage: | |
fc = nn.Linear(1,1) | |
optimizer = optim.Adam(fc.parameters()) | |
lr_scheduler = InterpolatingLogScheduler(optimizer, num_steps=400, min_lr=1e-6, max_lr=1e-4) | |
""" | |
self.num_steps = num_steps | |
self.min_lr = min_lr | |
self.max_lr = max_lr | |
self.q = (max_lr / min_lr) ** (1 / num_steps - 1) | |
super().__init__(optimizer, last_epoch) | |
def get_lr(self): | |
if self.last_epoch == 0: | |
lr = self.min_lr | |
elif self.last_epoch < self.num_steps: | |
# FIXME, not perfect as we need to account for number of steps are in an epoch, etc | |
lr = self.min_lr * (self.q ** self.last_epoch) | |
else: | |
lr = self.max_lr | |
return [lr for _ in self.base_lrs] | |