如何将Mish函数用到深度学习算法中

古城微笑少年丶 2022-12-23 13:28 90阅读 0赞

**目录**

摘要

如何在Pytorch使用Mish函数

如何在Keras中使用Mish激活函数。

--------------------

# 摘要 #

Diganta Misra的一篇题为“Mish: A Self Regularized Non-Monotonic Neural Activation Function”的新论文介绍了一个新的深度学习激活函数，该函数在最终准确度上比Swish(+.494%)和ReLU(+ 1.671%)都有提高

公式如下：

![/images/20221120/7c8040915fbe4f729bb5b1ddff72e103.png][https_imgconvert.csdnimg.cn_aHR0cHM6Ly9pbWcyMDE4LmNuYmxvZ3MuY29tL2Jsb2cvMTEwMjc5MS8yMDE5MTEvMTEwMjc5MS0yMDE5MTEwMzE3NTMwMTY4My0xNDc0NzQ0MTUxLnBuZw_x-oss-process_image_format_png]

![/images/20221120/05e406774af142129ac91c856e11de84.png][https_imgconvert.csdnimg.cn_aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X2pwZy9LWVNEVG1PVlp2b3E3aWJwaWJBRG5LZXRCa3RUNjFOT2lhajdpY2liM24ybVF3TmVKY1MyRDFFSGtCQW1aVURpY0s3aWIwUGlhR3JpYVV4ajdCeHh3MUE5U0hKaWJudEEvNjQwP3d4X2ZtdD1qcGVn_x-oss-process_image_format_png]

*  # 如何在Pytorch使用Mish函数 #

定义Mish函数。

class Mish(torch.nn.Module):
    
        def __init__(self):
    
            super().__init__()
    
    
    
        def forward(self, x):
    
            x = x * (torch.tanh(torch.nn.functional.softplus(x)))
    
            return x

调用函数：

class Path1_64(nn.Module):
    
        def __init__(self):
    
            super().__init__()
    
            self.conv1 = ConvBN(32, 64, 3)
    
            self.conv2 = ConvBN(64, 64, [1, 9])
    
            self.conv3 = ConvBN(64, 64, [9, 1])
    
            self.conv4 = ConvBN(64, 64, 1)
    
            self.resBlock = ResBlock(ch=64, nblocks=2)
    
            self.conv5 = ConvBN(64, 64, [1, 7])
    
            self.conv6 = ConvBN(64, 64, [7, 1])
    
            self.conv7 = ConvBN(64, 64, 1)
    
            self.relu = Mish()
    
    
    
        def forward(self, input):
    
            x1 = self.conv1(input)
    
            x2 = self.conv2(x1)
    
            x3 = self.conv3(x2)
    
            x4 = self.conv4(x3)
    
            r1 = self.resBlock(x4)
    
            x5 = self.conv5(r1)
    
            x6 = self.conv6(x5)
    
            x7 = self.conv7(x6)
    
            x7 = self.relu(x7 + x4)
    
            return x7

调用Mish激活函数和调用其他的激活函数一样，直接调用即可。

*  # 如何在Keras中使用Mish激活函数。 #

定义Mish激活函数

import tensorflow as tf
    from tensorflow.python.keras.layers import *
    from tensorflow.keras.layers import Activation
    from tensorflow.keras.utils import get_custom_objects
    
    
    
    class Mish(Activation):
    
        def __init__(self, activation, **kwargs):
    
            super(Mish, self).__init__(activation, **kwargs)
    
            self.__name__ = 'Mish'
    
    def mish(inputs):
    
        return inputs * tf.math.tanh(tf.math.softplus(inputs))
    
    get_custom_objects().update({'Mish': Mish(mish)})

调用激活函数：

def bn_prelu(x):
    
        x = BatchNormalization(epsilon=1e-5)(x)
    
        x = Activation('Mish')(x)
    
        return x
    
    def build_model(out_dims, input_shape=(100, 100, 3)):
    
        inputs_dim = Input(input_shape)
    
        x = Conv2D(32, (3, 3), strides=(2, 2), padding='same')(inputs_dim)
    
        x = bn_prelu(x)
    
        x = Conv2D(32, (3, 3), strides=(1, 1), padding='same')(x)
    
        x = bn_prelu(x)
    
        x = MaxPooling2D(pool_size=(2, 2))(x)
    
        x = Conv2D(64, (3, 3), strides=(1, 1), padding='same')(x)
    
        x = bn_prelu(x)
    
        x = Conv2D(64, (3, 3), strides=(1, 1), padding='same')(x)
    
        x = bn_prelu(x)
    
        x = MaxPooling2D(pool_size=(2, 2))(x)
    
        x = Conv2D(128, (3, 3), strides=(1, 1), padding='same')(x)
    
        x = bn_prelu(x)
    
        x = Conv2D(128, (3, 3), strides=(1, 1), padding='same')(x)
    
        x = bn_prelu(x)
    
        x = MaxPooling2D(pool_size=(2, 2))(x)
    
        x = Conv2D(256, (3, 3), strides=(1, 1), padding='same')(x)
    
        x = bn_prelu(x)
    
        x = Conv2D(256, (3, 3), strides=(1, 1), padding='same')(x)
    
        x = bn_prelu(x)
    
        x = GlobalAveragePooling2D()(x)
    
        dp_1 = Dropout(0.5)(x)
    
        fc2 = Dense(out_dims)(dp_1)
    
        fc2 = Activation('softmax')(fc2)  # 此处注意，为sigmoid函数
    
        model = Model(inputs=inputs_dim, outputs=fc2)
    
        return model
    
    
    
    model = build_model(2)  # 生成模型
    
    optimizer = Adam(lr=1e-3)  # 加入优化器，设置优化器的学习率。
    
    model.compile(optimizer=optimizer, loss='sparse_categorical_crossentropy', metrics=['accuracy'])

[https_imgconvert.csdnimg.cn_aHR0cHM6Ly9pbWcyMDE4LmNuYmxvZ3MuY29tL2Jsb2cvMTEwMjc5MS8yMDE5MTEvMTEwMjc5MS0yMDE5MTEwMzE3NTMwMTY4My0xNDc0NzQ0MTUxLnBuZw_x-oss-process_image_format_png]: /images/20221120/7c8040915fbe4f729bb5b1ddff72e103.png
[https_imgconvert.csdnimg.cn_aHR0cHM6Ly9tbWJpei5xcGljLmNuL21tYml6X2pwZy9LWVNEVG1PVlp2b3E3aWJwaWJBRG5LZXRCa3RUNjFOT2lhajdpY2liM24ybVF3TmVKY1MyRDFFSGtCQW1aVURpY0s3aWIwUGlhR3JpYVV4ajdCeHh3MUE5U0hKaWJudEEvNjQwP3d4X2ZtdD1qcGVn_x-oss-process_image_format_png]: /images/20221120/05e406774af142129ac91c856e11de84.png