如何解决 Keras 中的“模型尚未构建”错误？

Question

我在使用 CNN 时遇到了这个错误：

This model has not yet been built. Build the model first by calling `build()` or by calling the model on a batch of data.

我的代码如下：

 from tensorflow.keras.models import Sequential
 from tensorflow.keras.layers import Dense,Dropout
 from tensorflow.keras.layers import Conv2D
 from tensorflow.keras.layers import Flatten
 from tensorflow.keras.layers import MaxPooling2D
 from tensorflow.keras.callbacks import TensorBoard

 model=Sequential()
 model.add(Conv2D(32,5,input_shape=(1,28,28),activation='relu',data_format='channels_last'))
 model.add(MaxPooling2D(pool_size=(2,2),strides=2))
 model.add(Flatten())
 model.add(Conv2D(64,5,input_shape=(1,28,28),activation='relu',data_format='channels_last'))
 model.add(MaxPooling2D(pool_size=2,strides=2))
 model.add(Flatten())
 model.add(Dense(units=32,activation='relu'))
 model.add(Dropout(0.4))
 model.add(Dense(units=1,activation='softmax'))

 model.summary()

Answer 1

根据错误，运行：

input_shape=(1,28,28)
model.build(input_shape)                
model.summary()