mindspore/model_zoo/research/cv/tinynet/src/utils.py

# 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
#
# Unless 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.
# ============================================================================
"""model utils"""
import math
import argparse

import numpy as np


def str2bool(value):
    """Convert string arguments to bool type"""
    if value.lower() in ('yes', 'true', 't', 'y', '1'):
        return True
    if value.lower() in ('no', 'false', 'f', 'n', '0'):
        return False
    raise argparse.ArgumentTypeError('Boolean value expected.')


def get_lr(base_lr, total_epochs, steps_per_epoch, decay_epochs=1, decay_rate=0.9,
           warmup_epochs=0., warmup_lr_init=0., global_epoch=0):
    """Get scheduled learning rate"""
    lr_each_step = []
    total_steps = steps_per_epoch * total_epochs
    global_steps = steps_per_epoch * global_epoch
    self_warmup_delta = ((base_lr - warmup_lr_init) / \
                         warmup_epochs) if warmup_epochs > 0 else 0
    self_decay_rate = decay_rate if decay_rate < 1 else 1/decay_rate
    for i in range(total_steps):
        epochs = math.floor(i/steps_per_epoch)
        cond = 1 if (epochs < warmup_epochs) else 0
        warmup_lr = warmup_lr_init + epochs * self_warmup_delta
        decay_nums = math.floor(epochs / decay_epochs)
        decay_rate = math.pow(self_decay_rate, decay_nums)
        decay_lr = base_lr * decay_rate
        lr = cond * warmup_lr + (1 - cond) * decay_lr
        lr_each_step.append(lr)
    lr_each_step = lr_each_step[global_steps:]
    lr_each_step = np.array(lr_each_step).astype(np.float32)
    return lr_each_step


def add_weight_decay(net, weight_decay=1e-5, skip_list=None):
    """Apply weight decay to only conv and dense layers (len(shape) > =2)
    Args:
        net (mindspore.nn.Cell): Mindspore network instance
        weight_decay (float): weight decay tobe used.
        skip_list (tuple): list of parameter names without weight decay
    Returns:
        A list of group of parameters, separated by different weight decay.
    """
    decay = []
    no_decay = []
    if not skip_list:
        skip_list = ()
    for param in net.trainable_params():
        if len(param.shape) == 1 or \
           param.name.endswith(".bias") or \
           param.name in skip_list:
            no_decay.append(param)
        else:
            decay.append(param)
    return [
        {'params': no_decay, 'weight_decay': 0.},
        {'params': decay, 'weight_decay': weight_decay}]


def count_params(net):
    """Count number of parameters in the network
    Args:
        net (mindspore.nn.Cell): Mindspore network instance
    Returns:
        total_params (int): Total number of trainable params
    """
    total_params = 0
    for param in net.trainable_params():
        total_params += np.prod(param.shape)
    return total_params