32 lines
1.1 KiB
Python
Executable File
32 lines
1.1 KiB
Python
Executable File
from bisect import bisect_right
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from torch.optim.lr_scheduler import _LRScheduler
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class WarmupMultiStepLR(_LRScheduler):
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def __init__(self, optimizer, milestones, gamma=0.1, warmup_factor=1.0 / 3,
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warmup_iters=500, last_epoch=-1):
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if not list(milestones) == sorted(milestones):
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raise ValueError(
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"Milestones should be a list of" " increasing integers. Got {}",
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milestones,
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)
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self.milestones = milestones
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self.gamma = gamma
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self.warmup_factor = warmup_factor
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self.warmup_iters = warmup_iters
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super().__init__(optimizer, last_epoch)
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def get_lr(self):
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warmup_factor = 1
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if self.last_epoch < self.warmup_iters:
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alpha = float(self.last_epoch) / self.warmup_iters
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warmup_factor = self.warmup_factor * (1 - alpha) + alpha
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return [
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base_lr
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* warmup_factor
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* self.gamma ** bisect_right(self.milestones, self.last_epoch)
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for base_lr in self.base_lrs
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]
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