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- """ Step Scheduler
- Basic step LR schedule with warmup, noise.
- Hacked together by / Copyright 2020 Ross Wightman
- """
- import math
- import torch
- from typing import List
- from .scheduler import Scheduler
- class StepLRScheduler(Scheduler):
- """
- """
- def __init__(
- self,
- optimizer: torch.optim.Optimizer,
- decay_t: float,
- decay_rate: float = 1.,
- warmup_t=0,
- warmup_lr_init=0,
- warmup_prefix=True,
- t_in_epochs=True,
- noise_range_t=None,
- noise_pct=0.67,
- noise_std=1.0,
- noise_seed=42,
- initialize=True,
- ) -> None:
- super().__init__(
- optimizer,
- param_group_field="lr",
- t_in_epochs=t_in_epochs,
- noise_range_t=noise_range_t,
- noise_pct=noise_pct,
- noise_std=noise_std,
- noise_seed=noise_seed,
- initialize=initialize,
- )
- self.decay_t = decay_t
- self.decay_rate = decay_rate
- self.warmup_t = warmup_t
- self.warmup_lr_init = warmup_lr_init
- self.warmup_prefix = warmup_prefix
- if self.warmup_t:
- self.warmup_steps = [(v - warmup_lr_init) / self.warmup_t for v in self.base_values]
- super().update_groups(self.warmup_lr_init)
- else:
- self.warmup_steps = [1 for _ in self.base_values]
- def _get_lr(self, t: int) -> List[float]:
- if t < self.warmup_t:
- lrs = [self.warmup_lr_init + t * s for s in self.warmup_steps]
- else:
- if self.warmup_prefix:
- t = t - self.warmup_t
- lrs = [v * (self.decay_rate ** (t // self.decay_t)) for v in self.base_values]
- return lrs
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