!7951 Modelzoo retinaface, improvement of learning rate descent function.
Merge pull request !7951 from zhanghuiyao/4p_retinafacepull/7951/MERGE
commit
3b1694a762
@ -0,0 +1,61 @@
|
||||
# Copyright 2020 Huawei Technologies Co., Ltd
|
||||
#
|
||||
# Licensed under the Apache License, Version 2.0 (the "License");
|
||||
# you may not use this file except in compliance with the License.
|
||||
# You may obtain a copy of the License at
|
||||
#
|
||||
# http://www.apache.org/licenses/LICENSE-2.0
|
||||
#
|
||||
# less required by applicable law or agreed to in writing, software
|
||||
# distributed under the License is distributed on an "AS IS" BASIS,
|
||||
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
# See the License for the specific language governing permissions and
|
||||
# limitations under the License.
|
||||
# ============================================================================
|
||||
"""learning rate schedule."""
|
||||
import math
|
||||
from .config import cfg_res50
|
||||
|
||||
|
||||
def _linear_warmup_learning_rate(current_step, warmup_steps, base_lr, init_lr):
|
||||
lr_inc = (float(base_lr) - float(init_lr)) / float(warmup_steps)
|
||||
learning_rate = float(init_lr) + lr_inc * current_step
|
||||
return learning_rate
|
||||
|
||||
|
||||
def _a_cosine_learning_rate(current_step, base_lr, warmup_steps, decay_steps):
|
||||
base = float(current_step - warmup_steps) / float(decay_steps)
|
||||
learning_rate = (1 + math.cos(base * math.pi)) / 2 * base_lr
|
||||
return learning_rate
|
||||
|
||||
|
||||
def _dynamic_lr(base_lr, total_steps, warmup_steps, warmup_ratio=1 / 3):
|
||||
lr = []
|
||||
for i in range(total_steps):
|
||||
if i < warmup_steps:
|
||||
lr.append(_linear_warmup_learning_rate(i, warmup_steps, base_lr, base_lr * warmup_ratio))
|
||||
else:
|
||||
lr.append(_a_cosine_learning_rate(i, base_lr, warmup_steps, total_steps))
|
||||
|
||||
return lr
|
||||
|
||||
|
||||
def adjust_learning_rate(initial_lr, gamma, stepvalues, steps_pre_epoch, total_epochs, warmup_epoch=5):
|
||||
if cfg_res50['lr_type'] == 'dynamic_lr':
|
||||
return _dynamic_lr(initial_lr, total_epochs * steps_pre_epoch, warmup_epoch * steps_pre_epoch,
|
||||
warmup_ratio=1 / 3)
|
||||
|
||||
lr_each_step = []
|
||||
for epoch in range(1, total_epochs + 1):
|
||||
for _ in range(steps_pre_epoch):
|
||||
if epoch <= warmup_epoch:
|
||||
lr = 0.1 * initial_lr * (1.5849 ** (epoch - 1))
|
||||
else:
|
||||
if stepvalues[0] <= epoch <= stepvalues[1]:
|
||||
lr = initial_lr * (gamma ** (1))
|
||||
elif epoch > stepvalues[1]:
|
||||
lr = initial_lr * (gamma ** (2))
|
||||
else:
|
||||
lr = initial_lr
|
||||
lr_each_step.append(lr)
|
||||
return lr_each_step
|
Loading…
Reference in new issue