我在尝试创建一个针对MNIST数据集的变分自编码器(VAE)模型,希望能够绘制损失函数与训练轮次的关系图。然而,我遇到了一些问题,并且在网上找不到解决方案。在导入模块时,我使用了以下导入语句(仅为提供代码的背景):
from keras import backend as Kfrom keras.layers import Input, Dense, Lambda, Layer, Add, Multiplyfrom keras.models import Model, Sequentialfrom keras.datasets import mnist
我还创建了一个名为bn的函数,用于自定义损失计算,并创建了一个名为KLDivergenceLayer的类,用于在最终模型损失中添加KL散度层。
代码如下:
decoder = Sequential([ Dense(intermediate_dim, input_dim=latent_dim, activation='relu'), Dense(original_dim, activation='sigmoid')])x = Input(shape=(original_dim,))h = Dense(intermediate_dim, activation='relu')(x)z_mu = Dense(latent_dim)(h)z_log_var = Dense(latent_dim)(h)z_mu, z_log_var = KLDivergenceLayer()([z_mu, z_log_var])z_sigma = Lambda(lambda t: K.exp(.5*t))(z_log_var)eps = Input(tensor=K.random_normal(stddev=epsilon_std, shape=(K.shape(x)[0], latent_dim)))z_eps = Multiply()([z_sigma, eps])z = Add()([z_mu, z_eps])x_pred = decoder(z)vae = Model(inputs=[x, eps], outputs=x_pred)vae.compile(optimizer='rmsprop', loss=bn)# train the VAE on MNIST digits(x_train, y_train), (x_test, y_test) = mnist.load_data()x_train = x_train.reshape(-1, original_dim) / 255.x_test = x_test.reshape(-1, original_dim) / 255.vae.fit(x_train, x_train, shuffle=True, epochs=epochs, batch_size=batch_size, validation_data=(x_test, x_test))
我得到的错误信息如下:
ValueError: Layer model expects 2 input(s), but it received 1 input tensors. Inputs received: [<tf.Tensor 'IteratorGetNext:0' shape=(100, 784) dtype=float32>]
回答:
问题出在你的eps层,它并不是模型的输入。
你可以用一个简单的层来替代它,像这样:
eps = Lambda(lambda t: K.random_normal(stddev=1.0, shape=(K.shape(t)[0], latent_dim)))(z_log_var)
你可以在这里找到运行的笔记本:
https://colab.research.google.com/drive/1fLmfwCA_TOeOlXiiSabp4C4UKq73ofEN?usp=sharing