# Copyright (c) OpenMMLab. All rights reserved.
import math
from unittest import TestCase
import torch
import torch.nn.functional as F
import torch.optim as optim
from mmengine.optim.scheduler import (ConstantLR, CosineAnnealingLR,
ExponentialLR, LinearLR, MultiStepLR,
PolyLR, StepLR, _ParamScheduler)
from mmengine.testing import assert_allclose
class ToyModel(torch.nn.Module):
def __init__(self):
super().__init__()
self.conv1 = torch.nn.Conv2d(1, 1, 1)
self.conv2 = torch.nn.Conv2d(1, 1, 1)
def forward(self, x):
return self.conv2(F.relu(self.conv1(x)))
class TestLRScheduler(TestCase):
def setUp(self):
"""Setup the model and optimizer which are used in every test method.
TestCase calls functions in this order: setUp() -> testMethod() ->
tearDown() -> cleanUp()
"""
self.model = ToyModel()
self.optimizer = optim.SGD(
self.model.parameters(), lr=0.05, momentum=0.01, weight_decay=5e-4)
def test_base_scheduler_step(self):
with self.assertRaises(NotImplementedError):
_ParamScheduler(self.optimizer, param_name='lr')
def test_invalid_optimizer(self):
with self.assertRaisesRegex(TypeError, 'should be an Optimizer'):
StepLR('invalid_optimizer', step_size=1)
def test_overwrite_optimzer_step(self):
# raise warning if the counter in optimizer.step() is overwritten
scheduler = ExponentialLR(self.optimizer, gamma=0.9)
def overwrite_fun():
pass
self.optimizer.step = overwrite_fun
self.optimizer.step()
self.assertWarnsRegex(UserWarning, r'how-to-adjust-learning-rate',
scheduler.step)
def test_resume(self):
# test invalid case: optimizer and scheduler are not both resumed
with self.assertRaisesRegex(KeyError,
"param 'initial_lr' is not specified"):
StepLR(self.optimizer, gamma=0.1, step_size=3, last_step=10)
# test manually resume with ``last_step`` instead of load_state_dict
epochs = 10
targets = [0.05 * (0.9**x) for x in range(epochs)]
scheduler = ExponentialLR(self.optimizer, gamma=0.9)
results = []
for epoch in range(5):
for param_group in self.optimizer.param_groups:
results.append(param_group['lr'])
# The order should be
# train_epoch() -> save_checkpoint() -> scheduler.step().
# Break at here to simulate the checkpoint is saved before
# the scheduler.step().
if epoch == 4:
break
scheduler.step()
scheduler2 = ExponentialLR(self.optimizer, gamma=0.9, last_step=4)
for epoch in range(6):
for param_group in self.optimizer.param_groups:
results.append(param_group['lr'])
scheduler2.step()
for epoch in range(epochs):
assert_allclose(
targets[epoch],
results[epoch],
msg='lr is wrong in epoch {}: expected {}, got {}'.format(
epoch, targets[epoch], results[epoch]),
atol=1e-5,
rtol=0)
def test_scheduler_before_optim_warning(self):
"""warns if scheduler is used before optimizer."""
def call_sch_before_optim():
scheduler = StepLR(self.optimizer, gamma=0.1, step_size=3)
scheduler.step()
self.optimizer.step()
# check warning doc link
self.assertWarnsRegex(UserWarning, r'how-to-adjust-learning-rate',
call_sch_before_optim)
# check warning when resume
for i, group in enumerate(self.optimizer.param_groups):
group['initial_lr'] = 0.01
def call_sch_before_optim_resume():
scheduler = StepLR(
self.optimizer, gamma=0.1, step_size=3, last_step=10)
scheduler.step()
self.optimizer.step()
# check warning doc link
self.assertWarnsRegex(UserWarning, r'how-to-adjust-learning-rate',
call_sch_before_optim_resume)
def test_get_last_value(self):
epochs = 10
targets = [[0.05] * 3 + [0.005] * 3 + [0.0005] * 3 + [0.00005]]
scheduler = StepLR(self.optimizer, 3, gamma=0.1)
for epoch in range(epochs):
result = scheduler.get_last_value()
self.optimizer.step()
scheduler.step()
target = [t[epoch] for t in targets]
for t, r in zip(target, result):
assert_allclose(
target,
result,
msg='LR is wrong in epoch {}: expected {}, got {}'.format(
epoch, t, r),
atol=1e-5,
rtol=0)
def test_scheduler_step_count(self):
iteration = 10
scheduler = StepLR(self.optimizer, gamma=0.1, step_size=3)
self.assertEqual(scheduler.last_step, 0)
target = [i + 1 for i in range(iteration)]
step_counts = []
for i in range(iteration):
self.optimizer.step()
scheduler.step()
step_counts.append(scheduler.last_step)
self.assertEqual(step_counts, target)
def test_effective_interval(self):
# check invalid begin end
with self.assertRaisesRegex(ValueError,
'end should be larger than begin'):
StepLR(self.optimizer, gamma=0.1, step_size=3, begin=10, end=5)
# lr = 0.05 if epoch == 0
# lr = 0.025 if epoch == 1
# lr = 0.03125 if epoch == 2
# lr = 0.0375 if epoch == 3
# lr = 0.04375 if epoch == 4
# lr = 0.005 if epoch > 4
begin = 1
epochs = 10
start_factor = 1.0 / 2
iters = 4
interpolation = [
start_factor + i * (1 - start_factor) / iters for i in range(iters)
]
single_targets = [0.05] * begin + [x * 0.05
for x in interpolation] + [0.05] * (
epochs - iters - begin)
targets = [single_targets, [x * epochs for x in single_targets]]
scheduler = LinearLR(
self.optimizer,
start_factor=start_factor,
begin=begin,
end=begin + iters + 1)
self._test_scheduler_value(scheduler, targets, epochs)
def _test_scheduler_value(self,
schedulers,
targets,
epochs=10,
param_name='lr'):
if isinstance(schedulers, _ParamScheduler):
schedulers = [schedulers]
for epoch in range(epochs):
for param_group, target in zip(self.optimizer.param_groups,
targets):
assert_allclose(
target[epoch],
param_group[param_name],
msg='{} is wrong in epoch {}: expected {}, got {}'.format(
param_name, epoch, target[epoch],
param_group[param_name]),
atol=1e-5,
rtol=0)
[scheduler.step() for scheduler in schedulers]
def test_step_scheduler(self):
# lr = 0.05 if epoch < 3
# lr = 0.005 if 3 <= epoch < 6
# lr = 0.0005 if 6 <= epoch < 9
# lr = 0.00005 if epoch >=9
epochs = 10
single_targets = [0.05] * 3 + [0.005] * 3 + [0.0005] * 3 + [0.00005
] * 3
targets = [single_targets, [x * epochs for x in single_targets]]
scheduler = StepLR(
self.optimizer, gamma=0.1, step_size=3, verbose=True)
self._test_scheduler_value(scheduler, targets, epochs)
def test_multi_step_scheduler(self):
# lr = 0.05 if epoch < 2
# lr = 0.005 if 2 <= epoch < 5
# lr = 0.0005 if 5 <= epoch < 9
# lr = 0.00005 if epoch >= 9
epochs = 10
single_targets = [0.05] * 2 + [0.005] * 3 + [0.0005] * 4 + [0.00005
] * 3
targets = [single_targets, [x * epochs for x in single_targets]]
scheduler = MultiStepLR(
self.optimizer, gamma=0.1, milestones=[2, 5, 9])
self._test_scheduler_value(scheduler, targets, epochs)
def test_constant_scheduler(self):
# factor should between 0~1
with self.assertRaises(ValueError):
ConstantLR(self.optimizer, factor=99)
# lr = 0.025 if epoch < 5
# lr = 0.005 if 5 <= epoch
epochs = 10
single_targets = [0.025] * 4 + [0.05] * 6
targets = [single_targets, [x * epochs for x in single_targets]]
scheduler = ConstantLR(self.optimizer, factor=1.0 / 2, end=5)
self._test_scheduler_value(scheduler, targets, epochs)
def test_linear_scheduler(self):
with self.assertRaises(ValueError):
LinearLR(self.optimizer, start_factor=10, end=900)
with self.assertRaises(ValueError):
LinearLR(self.optimizer, start_factor=-1, end=900)
with self.assertRaises(ValueError):
LinearLR(self.optimizer, end_factor=1.001, end=900)
with self.assertRaises(ValueError):
LinearLR(self.optimizer, end_factor=-0.00001, end=900)
# lr = 0.025 if epoch == 0
# lr = 0.03125 if epoch == 1
# lr = 0.0375 if epoch == 2
# lr = 0.04375 if epoch == 3
# lr = 0.005 if epoch >= 4
epochs = 10
start_factor = 1.0 / 2
iters = 4
interpolation = [
start_factor + i * (1 - start_factor) / iters for i in range(iters)
]
single_targets = [x * 0.05 for x in interpolation] + [0.05] * (
epochs - iters)
targets = [single_targets, [x * epochs for x in single_targets]]
scheduler = LinearLR(
self.optimizer, start_factor=start_factor, end=iters + 1)
self._test_scheduler_value(scheduler, targets, epochs)
def test_exp_scheduler(self):
epochs = 10
single_targets = [0.05 * (0.9**x) for x in range(epochs)]
targets = [single_targets, [x * epochs for x in single_targets]]
scheduler = ExponentialLR(self.optimizer, gamma=0.9)
self._test_scheduler_value(scheduler, targets, epochs)
def test_cos_anneal_scheduler(self):
epochs = 12
t = 10
eta_min = 1e-10
single_targets = [
eta_min + (0.05 - eta_min) * (1 + math.cos(math.pi * x / t)) / 2
for x in range(epochs)
]
targets = [single_targets, [x * epochs for x in single_targets]]
scheduler = CosineAnnealingLR(self.optimizer, T_max=t, eta_min=eta_min)
self._test_scheduler_value(scheduler, targets, epochs)
def test_poly_scheduler(self):
epochs = 10
power = 0.9
min_lr = 0.001
iters = 4
single_targets = [
min_lr + (0.05 - min_lr) * (1 - i / iters)**power
for i in range(iters)
] + [min_lr] * (
epochs - iters)
targets = [single_targets, [x * epochs for x in single_targets]]
scheduler = PolyLR(
self.optimizer, power=power, eta_min=min_lr, end=iters + 1)
self._test_scheduler_value(scheduler, targets, epochs=10)
def _check_scheduler_state_dict(self, construct, construct2, epochs=10):
scheduler = construct()
for _ in range(epochs):
scheduler.optimizer.step()
scheduler.step()
scheduler_copy = construct2()
scheduler_copy.load_state_dict(scheduler.state_dict())
for key in scheduler.__dict__.keys():
if key != 'optimizer':
self.assertEqual(scheduler.__dict__[key],
scheduler_copy.__dict__[key])
self.assertEqual(scheduler.get_last_value(),
scheduler_copy.get_last_value())
def test_step_scheduler_state_dict(self):
self._check_scheduler_state_dict(
lambda: StepLR(self.optimizer, gamma=0.1, step_size=3),
lambda: StepLR(self.optimizer, gamma=0.01 / 2, step_size=1))
def test_multi_step_scheduler_state_dict(self):
self._check_scheduler_state_dict(
lambda: MultiStepLR(
self.optimizer, gamma=0.1, milestones=[2, 5, 9]),
lambda: MultiStepLR(
self.optimizer, gamma=0.01, milestones=[1, 4, 6]))
def test_exp_scheduler_state_dict(self):
self._check_scheduler_state_dict(
lambda: ExponentialLR(self.optimizer, gamma=0.1),
lambda: ExponentialLR(self.optimizer, gamma=0.01))
def test_cosine_scheduler_state_dict(self):
epochs = 10
eta_min = 1e-10
self._check_scheduler_state_dict(
lambda: CosineAnnealingLR(
self.optimizer, T_max=epochs, eta_min=eta_min),
lambda: CosineAnnealingLR(
self.optimizer, T_max=epochs // 2, eta_min=eta_min / 2),
epochs=epochs)
def test_linear_scheduler_state_dict(self):
epochs = 10
self._check_scheduler_state_dict(
lambda: LinearLR(self.optimizer, start_factor=1 / 3),
lambda: LinearLR(self.optimizer, start_factor=0, end_factor=0.3),
epochs=epochs)
def test_poly_scheduler_state_dict(self):
self._check_scheduler_state_dict(
lambda: PolyLR(self.optimizer, power=0.5, eta_min=0.001),
lambda: PolyLR(self.optimizer, power=0.8, eta_min=0.002),
epochs=10)
def test_multi_scheduler_without_overlap_linear_multi_step(self):
# use Linear in the first 5 epochs and then use MultiStep
epochs = 12
single_targets = [0.025, 0.03125, 0.0375, 0.04375
] + [0.05] * 4 + [0.005] * 3 + [0.0005] * 1
targets = [single_targets, [x * epochs for x in single_targets]]
scheduler1 = LinearLR(
self.optimizer, start_factor=1 / 2, begin=0, end=5)
scheduler2 = MultiStepLR(
self.optimizer, gamma=0.1, milestones=[3, 6], begin=5, end=12)
self._test_scheduler_value([scheduler1, scheduler2], targets, epochs)
def test_multi_scheduler_without_overlap_exp_cosine(self):
# in the first 5 epochs use Exp and then use Cosine
epochs = 10
single_targets1 = [0.05 * (0.9**x) for x in range(5)]
scheduler1 = ExponentialLR(self.optimizer, gamma=0.9, begin=0, end=5)
eta_min = 1e-10
single_targets2 = [
eta_min + (single_targets1[-1] - eta_min) *
(1 + math.cos(math.pi * x / 5)) / 2 for x in range(5)
]
single_targets = single_targets1 + single_targets2
targets = [single_targets, [x * epochs for x in single_targets]]
scheduler2 = CosineAnnealingLR(
self.optimizer, T_max=5, eta_min=eta_min, begin=5, end=10)
self._test_scheduler_value([scheduler1, scheduler2], targets, epochs)
def test_multi_scheduler_with_overlap(self):
# use Exp in the first 5 epochs and then use Cosine
epochs = 10
single_targets = [0.025, 0.03125, 0.0375, 0.004375
] + [0.005] * 2 + [0.0005] * 3 + [0.00005] * 1
targets = [single_targets, [x * epochs for x in single_targets]]
scheduler1 = LinearLR(
self.optimizer, start_factor=1 / 2, begin=0, end=5)
scheduler2 = MultiStepLR(
self.optimizer, gamma=0.1, milestones=[3, 6, 9])
self._test_scheduler_value([scheduler1, scheduler2], targets, epochs)
def test_multi_scheduler_with_gap(self):
# use Exp in the first 5 epochs and the last 5 epochs use Cosine
# no scheduler in the middle 5 epochs
epochs = 15
single_targets1 = [0.05 * (0.9**x) for x in range(5)]
scheduler1 = ExponentialLR(self.optimizer, gamma=0.9, begin=0, end=5)
eta_min = 1e-10
single_targets2 = [
eta_min + (single_targets1[-1] - eta_min) *
(1 + math.cos(math.pi * x / 5)) / 2 for x in range(5)
]
single_targets = single_targets1 + [single_targets1[-1]
] * 5 + single_targets2
targets = [single_targets, [x * epochs for x in single_targets]]
scheduler2 = CosineAnnealingLR(
self.optimizer, T_max=5, eta_min=eta_min, begin=10, end=15)
self._test_scheduler_value([scheduler1, scheduler2], targets, epochs)