Can't save a model with Lambda layer

[flamoedo]

Hi,

Although it has been subject of many correction, the problem still there, and I can't save the model with Lambda layer, using fit_generator. If I use fit (no batches) the problem don't occurs.

Error message:

UnicodeDecodeError: 'rawunicodeescape' codec can't decode bytes in position 80-84: truncated \uXXXX

If I switch to BatchNormalization, the model can be saved, but the loss is much higher then using a simple normalization, like X / 255 - 0.5 .

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[jorgecarleitao]

Can you provide a minimal and complete example that reproduces the issue?

[flamoedo]

Maybe would helps to know that it don't happens in windows server 2012.

Here is a example:

from keras.models import Sequential
from keras.layers import Flatten, Dense, Lambda, Conv2D, Cropping2D
from keras.layers import MaxPooling2D
from keras.layers.normalization import BatchNormalization

def cnn_model(input_shape):
    model = Sequential()
    model.add(Lambda(lambda x: x / 255.0 - 0.5, input_shape=input_shape))
    model.add(Cropping2D(cropping=((70,25),(0,0))))
    model.add(Conv2D(24,(5,5),strides=(2,2),activation='relu', padding='valid', kernel_initializer='he_normal'))
    model.add(Conv2D(36,(5,5),strides=(2,2),activation='relu', padding='valid', kernel_initializer='he_normal'))
    model.add(Conv2D(48,(5,5),strides=(2,2),activation='relu', padding='valid', kernel_initializer='he_normal'))
    model.add(Conv2D(64,(3,3),activation='relu', padding='valid', kernel_initializer='he_normal'))
    model.add(Conv2D(64,(3,3),activation='relu', padding='valid', kernel_initializer='he_normal'))
    model.add(Flatten())
    model.add(Dense(1164, kernel_initializer='he_normal'))
    model.add(Dense(100, kernel_initializer='he_normal'))
    model.add(Dense(50, kernel_initializer='he_normal'))
    model.add(Dense(10, kernel_initializer='he_normal'))
    model.add(Dense(1, kernel_initializer='he_normal'))
    
    return model

#Instantiating the model:
model = cnn_model((160,320,3))

#Try to save:
model.save('model.h5')

#Error:
#UnicodeDecodeError: 'rawunicodeescape' codec can't decode bytes in position 80-84: truncated \uXXXX

[FernanOrtega]

This issue was solved in this StackOverflow thread:

https://stackoverflow.com/questions/41847376/keras-model-to-json-error-rawunicodeescape-codec-cant-decode-bytes-in-posi

[profPlum]

I've got a similar issues except on a linux server and it's saying it can't pickle NotImplementedType object. Again trying to save a model with a lambda layer as an h5 file. What could be causing this?

[profPlum]

Actually looks like my problem has been mentioned and solved before #6442. Apparently lambda layers are just fragile when it comes to saving them to file, many gotchas, and it's often just better to make and use a custom layer (this what I ended up doing).