机器学习部分笔记

机器学习知识总结

AlexNet

https://gitee.com/Brief-rf/BlogImages/raw/master/img/image-20200823221333637.png

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graph TD
	a[输入图像:224x224x3]-->|ZeroPadding2D 1,2 1,2|b[227x227x3]
	b-->|卷积:11*11x48 s=4|c[55x55x48]
	c-->|池化:3*3 s=2|pool1[27x27x48]
	pool1-->|卷积:5*5x128 |d[27x27x128]
	d-->|池化:3*3 s=2|pool2[13x13x128]
	pool2-->|卷积:3*3x192|e[13x13x192]
	e-->|卷积:3*3x192|f[13x13x192]
	f-->|卷积:3*3x128|g[13x13x128]
	g-->|池化:3*3 s=2|pool3[6*5x128]
	pool3-->|展平|h[4608]
	h-->|全连接层一4608x2048|i[2048]
	i-->|全连接层二2048x2048|j[2048]
	j-->|全连接层三2048x1000|k[1000]
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from tensorflow.keras import layers, models, Model, Sequential


def AlexNet_v1(im_height=224, im_width=224, class_num=1000):
    # tensorflow中的tensor通道排序是NHWC
    input_image = layers.Input(shape=(im_height, im_width, 3), dtype="float32")  # output(None, 224, 224, 3)
    x = layers.ZeroPadding2D(((1, 2), (1, 2)))(input_image)                      # output(None, 227, 227, 3)
    x = layers.Conv2D(48, kernel_size=11, strides=4, activation="relu")(x)       # output(None, 55, 55, 48)
    x = layers.MaxPool2D(pool_size=3, strides=2)(x)                              # output(None, 27, 27, 48)
    x = layers.Conv2D(128, kernel_size=5, padding="same", activation="relu")(x)  # output(None, 27, 27, 128)
    x = layers.MaxPool2D(pool_size=3, strides=2)(x)                              # output(None, 13, 13, 128)
    x = layers.Conv2D(192, kernel_size=3, padding="same", activation="relu")(x)  # output(None, 13, 13, 192)
    x = layers.Conv2D(192, kernel_size=3, padding="same", activation="relu")(x)  # output(None, 13, 13, 192)
    x = layers.Conv2D(128, kernel_size=3, padding="same", activation="relu")(x)  # output(None, 13, 13, 128)
    x = layers.MaxPool2D(pool_size=3, strides=2)(x)                              # output(None, 6, 6, 128)

    x = layers.Flatten()(x)                         # output(None, 6*6*128)
    x = layers.Dropout(0.2)(x)
    x = layers.Dense(2048, activation="relu")(x)    # output(None, 2048)
    x = layers.Dropout(0.2)(x)
    x = layers.Dense(2048, activation="relu")(x)    # output(None, 2048)
    x = layers.Dense(class_num)(x)                  # output(None, 5)
    predict = layers.Softmax()(x)

    model = models.Model(inputs=input_image, outputs=predict)
    return model


class AlexNet_v2(Model):
    def __init__(self, class_num=1000):
        super(AlexNet_v2, self).__init__()
        self.features = Sequential([
            layers.ZeroPadding2D(((1, 2), (1, 2))),                                 # output(None, 227, 227, 3)
            layers.Conv2D(48, kernel_size=11, strides=4, activation="relu"),        # output(None, 55, 55, 48)
            layers.MaxPool2D(pool_size=3, strides=2),                               # output(None, 27, 27, 48)
            layers.Conv2D(128, kernel_size=5, padding="same", activation="relu"),   # output(None, 27, 27, 128)
            layers.MaxPool2D(pool_size=3, strides=2),                               # output(None, 13, 13, 128)
            layers.Conv2D(192, kernel_size=3, padding="same", activation="relu"),   # output(None, 13, 13, 192)
            layers.Conv2D(192, kernel_size=3, padding="same", activation="relu"),   # output(None, 13, 13, 192)
            layers.Conv2D(128, kernel_size=3, padding="same", activation="relu"),   # output(None, 13, 13, 128)
            layers.MaxPool2D(pool_size=3, strides=2)])                              # output(None, 6, 6, 128)

        self.flatten = layers.Flatten()
        self.classifier = Sequential([
            layers.Dropout(0.2),
            layers.Dense(1024, activation="relu"),                                  # output(None, 2048)
            layers.Dropout(0.2),
            layers.Dense(128, activation="relu"),                                   # output(None, 2048)
            layers.Dense(class_num),                                                # output(None, 5)
            layers.Softmax()
        ])

    def call(self, inputs, **kwargs):
        x = self.features(inputs)
        x = self.flatten(x)
        x = self.classifier(x)
        return x