tensorflow.keras.layers keras.Model 自定义层应用

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import  tensorflow as tf
from    tensorflow.keras import datasets, layers, optimizers, Sequential, metrics
from    tensorflow import keras

数据预处理

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def preprocess(x, y):
    """
    x is a simple image, not a batch
    """
    x = tf.cast(x, dtype=tf.float32) / 255.
    x = tf.reshape(x, [28*28])
    y = tf.cast(y, dtype=tf.int32)
    y = tf.one_hot(y, depth=10)
    return x,y
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自定义Layer
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class MyDense(layers.Layer):

	def __init__(self, inp_dim, outp_dim):
		super(MyDense, self).__init__()

		self.kernel = self.add_weight('w', [inp_dim, outp_dim])
		self.bias = self.add_weight('b', [outp_dim])

	def call(self, inputs, training=None):

		out = inputs @ self.kernel + self.bias

		return out

自定义Model

继承keras.Model可使用complie fit 等方法

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class MyModel(keras.Model):

	def __init__(self):
		super(MyModel, self).__init__()
        # 自定义5层网络
		self.fc1 = MyDense(28*28, 256)
		self.fc2 = MyDense(256, 128)
		self.fc3 = MyDense(128, 64)
		self.fc4 = MyDense(64, 32)
		self.fc5 = MyDense(32, 10)

	def call(self, inputs, training=None):
        # 定义网络传播过程
		x = self.fc1(inputs)
		x = tf.nn.relu(x)
		x = self.fc2(x)
		x = tf.nn.relu(x)
		x = self.fc3(x)
		x = tf.nn.relu(x)
		x = self.fc4(x)
		x = tf.nn.relu(x)
		x = self.fc5(x) 

		return x
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batchsz = 128
(x, y), (x_val, y_val) = datasets.mnist.load_data()
print('datasets:', x.shape, y.shape, x.min(), x.max())


db = tf.data.Dataset.from_tensor_slices((x,y))
db = db.map(preprocess).shuffle(60000).batch(batchsz)
ds_val = tf.data.Dataset.from_tensor_slices((x_val, y_val))
ds_val = ds_val.map(preprocess).batch(batchsz) 

sample = next(iter(db))
print(sample[0].shape, sample[1].shape)
datasets: (60000, 28, 28) (60000,) 0 255
(128, 784) (128, 10)

创建模型

summary()必须在fit 或 build之后使用

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network = MyModel()
network.build(input_shape=(None, 28*28))
# summary()必须在fit 或 build之后使用
network.summary()

network.compile(optimizer=optimizers.Adam(lr=0.01),
		loss=tf.losses.CategoricalCrossentropy(from_logits=True),
		metrics=['accuracy']
	)

network.fit(db, epochs=5, validation_data=ds_val,
              validation_freq=2)


network.evaluate(ds_val)
Model: "my_model_8"
_________________________________________________________________
Layer (type)                 Output Shape              Param #   
=================================================================
my_dense_40 (MyDense)        multiple                  200960    
_________________________________________________________________
my_dense_41 (MyDense)        multiple                  32896     
_________________________________________________________________
my_dense_42 (MyDense)        multiple                  8256      
_________________________________________________________________
my_dense_43 (MyDense)        multiple                  2080      
_________________________________________________________________
my_dense_44 (MyDense)        multiple                  330       
=================================================================
Total params: 244,522
Trainable params: 244,522
Non-trainable params: 0
_________________________________________________________________
Epoch 1/5
469/469 [==============================] - 10s 22ms/step - loss: 0.3078 - accuracy: 0.9076
Epoch 2/5
469/469 [==============================] - 13s 28ms/step - loss: 0.1409 - accuracy: 0.9600 - val_loss: 0.1318 - val_accuracy: 0.9641
Epoch 3/5
469/469 [==============================] - 13s 27ms/step - loss: 0.1125 - accuracy: 0.9680
Epoch 4/5
469/469 [==============================] - 16s 35ms/step - loss: 0.0984 - accuracy: 0.9724 - val_loss: 0.1196 - val_accuracy: 0.9673
Epoch 5/5
469/469 [==============================] - 15s 32ms/step - loss: 0.0875 - accuracy: 0.9760
79/79 [==============================] - 3s 33ms/step - loss: 0.1224 - accuracy: 0.9704





[0.12237951139141393, 0.9704]

模型预测

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sample = next(iter(ds_val))
x = sample[0]
y = sample[1] # one-hot
pred = network.predict(x) # [b, 10]
# convert back to number 
y = tf.argmax(y, axis=1)
pred = tf.argmax(pred, axis=1)

print(pred)
print(y)
tf.Tensor(
[7 2 1 0 4 1 4 9 6 9 0 6 9 0 1 5 9 7 3 4 9 6 6 5 4 0 7 4 0 1 3 1 3 4 7 2 7
 1 2 1 1 7 4 2 3 5 1 2 4 4 6 3 5 5 6 0 4 1 9 5 7 8 9 3 7 4 6 4 3 0 7 0 2 9
 1 7 3 2 9 7 7 6 2 7 8 4 7 3 6 1 3 6 9 3 1 4 1 7 6 9 6 0 5 4 9 9 2 1 9 4 8
 7 3 9 7 9 4 4 9 2 5 4 7 6 7 9 0 5], shape=(128,), dtype=int64)
tf.Tensor(
[7 2 1 0 4 1 4 9 5 9 0 6 9 0 1 5 9 7 3 4 9 6 6 5 4 0 7 4 0 1 3 1 3 4 7 2 7
 1 2 1 1 7 4 2 3 5 1 2 4 4 6 3 5 5 6 0 4 1 9 5 7 8 9 3 7 4 6 4 3 0 7 0 2 9
 1 7 3 2 9 7 7 6 2 7 8 4 7 3 6 1 3 6 9 3 1 4 1 7 6 9 6 0 5 4 9 9 2 1 9 4 8
 7 3 9 7 4 4 4 9 2 5 4 7 6 7 9 0 5], shape=(128,), dtype=int64)