Experimenting with per-epoch learning rate noise w/ step scheduler

Author: rwightman

timm/scheduler/scheduler_factory.py

@@ -33,11 +33,18 @@ def create_scheduler(args, optimizer):
         )
         num_epochs = lr_scheduler.get_cycle_length() + args.cooldown_epochs
     elif args.sched == 'step':
+        if isinstance(args.lr_noise, (list, tuple)):
+            noise_range = [n * num_epochs for n in args.lr_noise]
+        else:
+            noise_range = args.lr_noise * num_epochs
+        print(noise_range)
         lr_scheduler = StepLRScheduler(
             optimizer,
             decay_t=args.decay_epochs,
             decay_rate=args.decay_rate,
             warmup_lr_init=args.warmup_lr,
             warmup_t=args.warmup_epochs,
+            noise_range_t=noise_range,
+            noise_std=args.lr_noise_std,
         )
     return lr_scheduler, num_epochs

timm/scheduler/step_lr.py

@@ -14,14 +14,19 @@ def __init__(self,
                  decay_rate: float = 1.,
                  warmup_t=0,
                  warmup_lr_init=0,
+                 noise_range_t=None,
+                 noise_std=1.0,
                  t_in_epochs=True,
-                 initialize=True) -> None:
+                 initialize=True,
+                 ) -> None:
         super().__init__(optimizer, param_group_field="lr", 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.noise_range_t = noise_range_t
+        self.noise_std = noise_std
         self.t_in_epochs = t_in_epochs
         if self.warmup_t:
             self.warmup_steps = [(v - warmup_lr_init) / self.warmup_t for v in self.base_values]
@@ -33,8 +38,18 @@ def _get_lr(self, t):
         if t < self.warmup_t:
             lrs = [self.warmup_lr_init + t * s for s in self.warmup_steps]
         else:
-            lrs = [v * (self.decay_rate ** (t // self.decay_t))
-                   for v in self.base_values]
+            lrs = [v * (self.decay_rate ** (t // self.decay_t)) for v in self.base_values]
+        if self.noise_range_t is not None:
+            if isinstance(self.noise_range_t, (list, tuple)):
+                apply_noise = self.noise_range_t[0] <= t < self.noise_range_t[1]
+            else:
+                apply_noise = t >= self.noise_range_t
+            if apply_noise:
+                g = torch.Generator()
+                g.manual_seed(t)
+                lr_mult = torch.randn(1, generator=g).item() * self.noise_std + 1.
+                lrs = [min(5 * v, max(v / 5, v * lr_mult)) for v in lrs]
+                print(lrs)
         return lrs
 
     def get_epoch_values(self, epoch: int):

train.py

@@ -105,6 +105,10 @@
                     help='LR scheduler (default: "step"')
 parser.add_argument('--lr', type=float, default=0.01, metavar='LR',
                     help='learning rate (default: 0.01)')
+parser.add_argument('--lr-noise', type=float, nargs='+', default=None, metavar='pct, pct',
+                    help='learning rate noise on/off epoch percentages')
+parser.add_argument('--lr-noise-std', type=float, default=1.0, metavar='STDDEV',
+                    help='learning rate nose std-dev (default: 1.0)')
 parser.add_argument('--warmup-lr', type=float, default=0.0001, metavar='LR',
                     help='warmup learning rate (default: 0.0001)')
 parser.add_argument('--min-lr', type=float, default=1e-5, metavar='LR',