无法获取自定义层内 keras 层的输出形状

Question

我使用的是由多个Keras层构建的Keras自定义层。我试图从回调(on_train_batch_end(中获取内层的output_shape，并得到以下错误："AttributeError：从未调用过层，因此没有定义的输入形状">

我不明白如果调用自定义层中的调用函数，怎么会发生这种情况，因为我已经为单个批次训练了模型。

一个代码示例：

from tensorflow.keras.layers import  ReLU, MaxPooling2D, Input, Dense, Conv2D, Flatten
from tensorflow.keras.layers import Layer
from tensorflow.keras.models import Model
from tensorflow.keras.callbacks import Callback
import tensorflow as tf
import numpy as np

class MyLayer(Layer):
def __init__(self):
super(MyLayer, self).__init__()
self.conv = None
self.m_max = None
self.relu = None
def call(self, inputs, **kwargs):
x = self.conv(inputs)
x = self.m_max(x)
return self.relu(x)
def build(self, input_shape):
self.conv = Conv2D(input_shape=input_shape, filters=128, kernel_size=(2,2))
self.m_max = MaxPooling2D()
self.relu = ReLU()

class ModelCallback(Callback):
def on_batch_end(self, batch, logs=None):
print(self.model.layers[1].conv.output_shape)
inp = Input((32,32,3))
x = MyLayer()(inp)
x = Flatten()(x)
out = Dense(1)(x)
model = Model(inputs=inp, outputs=out)
model.compile(optimizer='adam', loss='categorical_crossentropy' )
x_train = np.random.rand(5000,32,32,3)
y_train = np.random.randint(2, size=(5000,1))
model.fit(x_train, y_train,epochs=5, callbacks=ModelCallback())

Answer 1

这不是一个真正的答案，但我会为其他人分享我的解决方法。这个想法只是计算伪数据的大小并保存它们。

def _calculate_shape(self, input_tensor_shape: tf.TensorShape):
self.conv.trainable = False
self.m_max.trainable = False
self.relu.trainable = False
input_shape = list(input_tensor_shape)
input_shape[0] = self.batch_size
x = self.conv(np.random.rand(*input_shape))
self.conv_shapes = (input_shape[1:], tf.shape(x).numpy().tolist()[1:])     # [1:] is needed to remove the batch size form the shape
x = self.m_max(x)
self.max_shapes = (self.conv_shapes[1], tf.shape(x).numpy().tolist()[1:])
x = self.relu(x)
self.relu_shapes = (self.max_shapes[1], tf.shape(x).numpy().tolist()[1:])
self.conv.trainable = True
self.m_max.trainable = True
self.relu.trainable = True

然后，您可以在尝试获取内层的形状时使用这些变量
**这将从形状中删除批量大小