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I have a dataset of 1-D vectors each 3001 digits long. I have used a simple convolutional network to perform binary classification on these sequences:

shape=train_X.shape[1:]
model = Sequential()
model.add(Conv1D(75,3,strides=1, input_shape=shape, activation='relu'))
model.add(MaxPooling1D(3))
model.add(Flatten())
model.add(Dense(1, activation='sigmoid'))
model.compile(loss='binary_crossentropy', optimizer='rmsprop', metrics=['accuracy'])

The network achieves ~60% accuracy. I now would like to create an autoencoder to discover the regular pattern that is distinguishing samples where the label is '1' vs those where it is '0'. i.e. to generate an exemplary sequence- that is representative of the '1' labeled samples.

Based on previous blogs and posts I have tried to put together an autoencoder that can achieve this: 

input_sig = Input(batch_shape=(None,3001,1))
x = Conv1D(64,3, activation='relu', padding='same')(input_sig)
x1 = MaxPooling1D(2)(x)
x2 = Conv1D(32,3, activation='relu', padding='same')(x1)
x3 = MaxPooling1D(2)(x2)
flat = Flatten()(x3)
encoded = Dense(1,activation = 'relu')(flat)
x2_ = Conv1D(32, 3, activation='relu', padding='same')(x3)
x1_ = UpSampling1D(2)(x2_)
x_ = Conv1D(64, 3, activation='relu', padding='same')(x1_)
upsamp = UpSampling1D(2)(x_)
decoded = Conv1D(1, 3, activation='sigmoid', padding='same')(upsamp)
autoencoder = Model(input_sig, decoded)
autoencoder.compile(optimizer='adam', loss='mse', metrics=['accuracy'])

This looks as follows:

autoencoder.summary()
_________________________________________________________________
Layer (type)                 Output Shape              Param #   
=================================================================
input_57 (InputLayer)        (None, 3001, 1)           0         
_________________________________________________________________
conv1d_233 (Conv1D)          (None, 3001, 64)          256       
_________________________________________________________________
max_pooling1d_115 (MaxPoolin (None, 1500, 64)          0         
_________________________________________________________________
conv1d_234 (Conv1D)          (None, 1500, 32)          6176      
_________________________________________________________________
max_pooling1d_116 (MaxPoolin (None, 750, 32)           0         
_________________________________________________________________
conv1d_235 (Conv1D)          (None, 750, 32)           3104      
_________________________________________________________________
up_sampling1d_106 (UpSamplin (None, 1500, 32)          0         
_________________________________________________________________
conv1d_236 (Conv1D)          (None, 1500, 64)          6208      
_________________________________________________________________
up_sampling1d_107 (UpSamplin (None, 3000, 64)          0         
_________________________________________________________________
conv1d_237 (Conv1D)          (None, 3000, 64)          12352     
=================================================================
Total params: 28,096
Trainable params: 28,096
Non-trainable params: 0

hence everything seems to be going smoothly until I train the netowrk

autoencoder.fit(train_X,train_y,epochs=3,batch_size=100,validation_data=(test_X, test_y))

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/bsxcto/miniconda3/lib/python3.6/site-packages/keras/engine/training.py", line 1630, in fit
    batch_size=batch_size)
  File "/home/bsxcto/miniconda3/lib/python3.6/site-packages/keras/engine/training.py", line 1480, in _standardize_user_data
    exception_prefix='target')
  File "/home/bsxcto/miniconda3/lib/python3.6/site-packages/keras/engine/training.py", line 113, in _standardize_input_data
    'with shape ' + str(data_shape))
ValueError: Error when checking target: expected conv1d_237 to have 3 dimensions, but got array with shape (32318, 1)

Hence I have tried adding a 'Reshape' layer before the last one.

upsamp = UpSampling1D(2)(x_)
flat = Flatten()(upsamp)
reshaped = Reshape((3000,64))(flat)
decoded = Conv1D(1, 3, activation='sigmoid', padding='same')(reshaped)

in which case the network looks as follows:

autoencoder.summary()
_________________________________________________________________
Layer (type)                 Output Shape              Param #   
=================================================================
input_59 (InputLayer)        (None, 3001, 1)           0         
_________________________________________________________________
conv1d_243 (Conv1D)          (None, 3001, 64)          256       
_________________________________________________________________
max_pooling1d_119 (MaxPoolin (None, 1500, 64)          0         
_________________________________________________________________
conv1d_244 (Conv1D)          (None, 1500, 32)          6176      
_________________________________________________________________
max_pooling1d_120 (MaxPoolin (None, 750, 32)           0         
_________________________________________________________________
conv1d_245 (Conv1D)          (None, 750, 32)           3104      
_________________________________________________________________
up_sampling1d_110 (UpSamplin (None, 1500, 32)          0         
_________________________________________________________________
conv1d_246 (Conv1D)          (None, 1500, 64)          6208      
_________________________________________________________________
up_sampling1d_111 (UpSamplin (None, 3000, 64)          0         
_________________________________________________________________
flatten_111 (Flatten)        (None, 192000)            0         
_________________________________________________________________
reshape_45 (Reshape)         (None, 3000, 64)          0         
_________________________________________________________________
conv1d_247 (Conv1D)          (None, 3000, 1)           193       
=================================================================
Total params: 15,937
Trainable params: 15,937
Non-trainable params: 0

But the same error results:

Error when checking target: expected conv1d_247 to have 3 dimensions, but got array with shape (32318, 1)

My questions are:

1) Is this a feasible way of finding the pattern that is distinguishing samples with label '1' vs '0'?

2) how can I make the final layer accept the final output of the last upsampling layer?

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1 Answers1

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original = Sequential() 
original.add(Conv1D(75,repeat_length,strides=stride, input_shape=shape, activation='relu’,padding=‘same’))
original.add(MaxPooling1D(repeat_length))   
original.add(Flatten()) 
original.add(Dense(1, activation='sigmoid'))    
original.compile(loss='binary_crossentropy', optimizer='rmsprop', metrics=['accuracy']) 
calculate_roc(original......)

mod=Sequential()
mod.add(original.layers[0])
mod.add(original.layers[1]) 
mod.add(Conv1D(75,window, activation='relu', padding='same'))   
mod.add(UpSampling1D(window))   
mod.add(Conv1D(1, 1, activation='sigmoid', padding='same'))
mod.compile(optimizer='adam', loss='mse', metrics=['accuracy']) 
mod.layers[0].trainable=False   
mod.layers[1].trainable=False   
mod.fit(train_X,train_X,epochs=1,batch_size=100)
decoded_imgs = mod.predict(test_X)  
x=decoded_imgs.mean(axis=0) 
plt.plot(x)
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