Mindspore | lenet 模型代码

1、创建数据集

import mindspore.dataset as ds
import mindspore.dataset.vision.c_transforms as CV
import mindspore.dataset.transforms.c_transforms as C
from mindspore.dataset.vision import Inter
from mindspore.common import dtype as mstype


def create_dataset(data_path, batch_size=32, repeat_size=1,
                   num_parallel_workers=1):
    """
    create dataset for train or test
    """
    # define dataset
    mnist_ds = ds.MnistDataset(data_path)

    resize_height, resize_width = 32, 32
    rescale = 1.0 / 255.0
    shift = 0.0
    rescale_nml = 1 / 0.3081
    shift_nml = -1 * 0.1307 / 0.3081

    # define map operations
    resize_op = CV.Resize((resize_height, resize_width), interpolation=Inter.LINEAR)  # Bilinear mode 双线性方式  调整输入图像大小
    rescale_nml_op = CV.Rescale(rescale_nml, shift_nml)   #张量操作以重新缩放输入图像,两个参数parameters( Rescale factor，Shift factor) 缩放和转移因子
    rescale_op = CV.Rescale(rescale, shift)   
    hwc2chw_op = CV.HWC2CHW()  #转置输入图像
    type_cast_op = C.TypeCast(mstype.int32)  #转换给定的数据类型

    # apply map operations on images
    mnist_ds = mnist_ds.map(operations=type_cast_op, input_columns="label", num_parallel_workers=num_parallel_workers)
    mnist_ds = mnist_ds.map(operations=resize_op, input_columns="image", num_parallel_workers=num_parallel_workers)
    mnist_ds = mnist_ds.map(operations=rescale_op, input_columns="image", num_parallel_workers=num_parallel_workers)
    mnist_ds = mnist_ds.map(operations=rescale_nml_op, input_columns="image", num_parallel_workers=num_parallel_workers)
    mnist_ds = mnist_ds.map(operations=hwc2chw_op, input_columns="image", num_parallel_workers=num_parallel_workers)

    # apply DatasetOps
    buffer_size = 10000
    mnist_ds = mnist_ds.shuffle(buffer_size=buffer_size)  # 打乱数据，设置缓冲区大小为10000
    mnist_ds = mnist_ds.batch(batch_size, drop_remainder=True) #设置每批training数据的大小，每32个数据为一个数组，丢弃多余剩下
    mnist_ds = mnist_ds.repeat(repeat_size)  #对数据做重复，每次数据都是不同的

    return mnist_ds

2、lenet模型

import mindspore.nn as nn
from mindspore.common.initializer import Normal


class LeNet5(nn.Cell):
    """
    Lenet network

    Args:
        num_class (int): Number of classes. Default: 10.
        num_channel (int): Number of channels. Default: 1.

    Returns:
        Tensor, output tensor
    Examples:
        >>> LeNet(num_class=10)

    """
    def __init__(self, num_class=10, num_channel=1, include_top=True):
        super(LeNet5, self).__init__()
        self.conv1 = nn.Conv2d(num_channel, 6, 5, pad_mode='valid')    #2维卷积 参数：（input_channel , output_channel , kernel_size , pad_mode）   
        self.conv2 = nn.Conv2d(6, 16, 5, pad_mode='valid')
        self.relu = nn.ReLU()     #线性激活函数 ReLU(x)=max(0,x),
        self.max_pool2d = nn.MaxPool2d(kernel_size=2, stride=2)   #池化层
        self.include_top = include_top
        if self.include_top:
            self.flatten = nn.Flatten()      #展平张量而不改变第 0 轴上批量大小的维度。
            self.fc1 = nn.Dense(16 * 5 * 5, 120, weight_init=Normal(0.02))   
            self.fc2 = nn.Dense(120, 84, weight_init=Normal(0.02))
            self.fc3 = nn.Dense(84, num_class, weight_init=Normal(0.02))


    def construct(self, x):
        x = self.conv1(x)
        x = self.relu(x)
        x = self.max_pool2d(x)
        x = self.conv2(x)
        x = self.relu(x)
        x = self.max_pool2d(x)
        if not self.include_top:
            return x
        x = self.flatten(x)
        x = self.relu(self.fc1(x))
        x = self.relu(self.fc2(x))
        x = self.fc3(x)
        return x

# 实例化网络
net = LeNet5()

# 定义损失函数
net_loss = nn.SoftmaxCrossEntropyWithLogits(sparse=True, reduction='mean')

# 定义优化器
net_opt = nn.Momentum(net.trainable_params(), learning_rate=0.01, momentum=0.9)

# 设置模型保存参数
# 每125steps保存一次模型参数，最多保留15个文件
config_ck = CheckpointConfig(save_checkpoint_steps=125, keep_checkpoint_max=15)
# 应用模型保存参数
ckpoint = ModelCheckpoint(prefix="checkpoint_lenet", config=config_ck)


def train_net(args, model, epoch_size, data_path, repeat_size, ckpoint_cb, sink_mode):
    """定义训练的方法"""
    # 加载训练数据集
    ds_train = create_dataset(os.path.join(data_path, "train"), 32, repeat_size)
    model.train(epoch_size, ds_train, callbacks=[ckpoint_cb, LossMonitor(125)], dataset_sink_mode=sink_mode)


def test_net(network, model, data_path):
    """定义验证的方法"""
    ds_eval = create_dataset(os.path.join(data_path, "test"))
    acc = model.eval(ds_eval, dataset_sink_mode=False)
    print("{}".format(acc))


mnist_path = "./datasets/MNIST_Data"
train_epoch = 1
dataset_size = 1
model = Model(net, net_loss, net_opt, metrics={"Accuracy": Accuracy()})
train_net(args, model, train_epoch, mnist_path, dataset_size, ckpoint, False)
test_net(net, model, mnist_path)