text: # 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.
  # ============================================================================
  """
  #################train vgg16 example on cifar10########################
  python train.py --data_path=$DATA_HOME --device_id=$DEVICE_ID
  """
  import argparse
  import os
  import random
  import numpy as np
  import mindspore.nn as nn
  from mindspore import Tensor
  from mindspore.communication.management import init
  from mindspore.nn.optim.momentum import Momentum
  from mindspore.train.model import Model, ParallelMode
  from mindspore import context
  from mindspore.train.callback import ModelCheckpoint, CheckpointConfig, LossMonitor, TimeMonitor
  from mindspore.model_zoo.vgg import vgg16
  from dataset import create_dataset
  from config import cifar_cfg as cfg
  random.seed(1)
  np.random.seed(1)
  
  def lr_steps(global_step, lr_max=None, total_epochs=None, steps_per_epoch=None):
      """Set learning rate."""
      lr_each_step = []
      total_steps = steps_per_epoch * total_epochs
      decay_epoch_index = [0.3 * total_steps, 0.6 * total_steps, 0.8 * total_steps]
      for i in range(total_steps):
          if i < decay_epoch_index[0]:
              lr_each_step.append(lr_max)
          elif i < decay_epoch_index[1]:
              lr_each_step.append(lr_max * 0.1)
          elif i < decay_epoch_index[2]:
              lr_each_step.append(lr_max * 0.01)
          else:
              lr_each_step.append(lr_max * 0.001)
      current_step = global_step
      lr_each_step = np.array(lr_each_step).astype(np.float32)
      learning_rate = lr_each_step[current_step:]
  
      return learning_rate
  
  
  if __name__ == '__main__':
      parser = argparse.ArgumentParser(description='Cifar10 classification')
      parser.add_argument('--device_target', type=str, default='Ascend', choices=['Ascend', 'GPU'],
                          help='device where the code will be implemented. (Default: Ascend)')
      parser.add_argument('--data_path', type=str, default='./cifar', help='path where the dataset is saved')
      parser.add_argument('--device_id', type=int, default=None, help='device id of GPU or Ascend. (Default: None)')
      args_opt = parser.parse_args()
  
      context.set_context(mode=context.GRAPH_MODE, device_target=args_opt.device_target)
      context.set_context(device_id=args_opt.device_id)
  
      device_num = int(os.environ.get("DEVICE_NUM", 1))
      if device_num > 1:
          context.reset_auto_parallel_context()
          context.set_auto_parallel_context(device_num=device_num, parallel_mode=ParallelMode.DATA_PARALLEL,
                                            mirror_mean=True)
          init()
  
      dataset = create_dataset(args_opt.data_path, cfg.epoch_size)
      batch_num = dataset.get_dataset_size()
  
      net = vgg16(num_classes=cfg.num_classes)
      lr = lr_steps(0, lr_max=cfg.lr_init, total_epochs=cfg.epoch_size, steps_per_epoch=batch_num)
      opt = Momentum(filter(lambda x: x.requires_grad, net.get_parameters()), Tensor(lr), cfg.momentum, weight_decay=cfg.weight_decay)
      loss = nn.SoftmaxCrossEntropyWithLogits(sparse=True, reduction='mean', is_grad=False)
      model = Model(net, loss_fn=loss, optimizer=opt, metrics={'acc'},
                    amp_level="O2", keep_batchnorm_fp32=False, loss_scale_manager=None)
  
      config_ck = CheckpointConfig(save_checkpoint_steps=batch_num * 5, keep_checkpoint_max=cfg.keep_checkpoint_max)
      time_cb = TimeMonitor(data_size=batch_num)
      ckpoint_cb = ModelCheckpoint(prefix="train_vgg_cifar10", directory="./", config=config_ck)
      loss_cb = LossMonitor()
      model.train(cfg.epoch_size, dataset, callbacks=[time_cb, ckpoint_cb, loss_cb])
      print("train success")
  