How to calculate the softmax in LSTM auto-encoder for input with zero padding












1















I am implementing a LSTM auto-encoder that with the input x and hopefully get the same output as x. However, I have several questions in the implementing, and please see my codes below:



dict_size = 10
max_sentence_length = 5
embed_dim = 20

x = Input(shape=(max_sentence_length,), dtype='int32')
encoder_input = Embedding(dict_size, embed_dim)(x)
encoder_output=LSTM(32, return_sequences=True)(encoder_input)
deocder_output = LSTM(32, return_sequences=True)(encoder_output)
y = Dense(dict_size, activation='softmax')(deocder_output)

model = Model(inputs=x, outputs=y)
model.compile(optimizer='adam', loss='categorical_crossentropy', metrics=['accuracy'])
print(model.summary())

train_x = np.array([[3, 1, 2]])
train_x = pad_sequences(train_x, max_sentence_length, padding='post')
train_y = np_utils.to_categorical(train_x, dict_size)

model.fit(train_x, train_y, batch_size=1, epochs=1)
predict_y = model.predict(train_x)
print(predict_y)


In this codes, the first problem is that : "ValueError: Error when checking target: expected dense_1 to have 3 dimensions, but got array with shape (5, 10)", I really do not know how to solve this problem first.



The second question is that, the length of x is 3, while with extra padding its length becomes to 5; At the final stage, the output would be a 5x10 matrix, i.e., the last two elements of the final output should not participate into the calculation of the softmax. Is there any way to fix this problem quickly?



Many many thanks!










share|improve this question





























    1















    I am implementing a LSTM auto-encoder that with the input x and hopefully get the same output as x. However, I have several questions in the implementing, and please see my codes below:



    dict_size = 10
    max_sentence_length = 5
    embed_dim = 20

    x = Input(shape=(max_sentence_length,), dtype='int32')
    encoder_input = Embedding(dict_size, embed_dim)(x)
    encoder_output=LSTM(32, return_sequences=True)(encoder_input)
    deocder_output = LSTM(32, return_sequences=True)(encoder_output)
    y = Dense(dict_size, activation='softmax')(deocder_output)

    model = Model(inputs=x, outputs=y)
    model.compile(optimizer='adam', loss='categorical_crossentropy', metrics=['accuracy'])
    print(model.summary())

    train_x = np.array([[3, 1, 2]])
    train_x = pad_sequences(train_x, max_sentence_length, padding='post')
    train_y = np_utils.to_categorical(train_x, dict_size)

    model.fit(train_x, train_y, batch_size=1, epochs=1)
    predict_y = model.predict(train_x)
    print(predict_y)


    In this codes, the first problem is that : "ValueError: Error when checking target: expected dense_1 to have 3 dimensions, but got array with shape (5, 10)", I really do not know how to solve this problem first.



    The second question is that, the length of x is 3, while with extra padding its length becomes to 5; At the final stage, the output would be a 5x10 matrix, i.e., the last two elements of the final output should not participate into the calculation of the softmax. Is there any way to fix this problem quickly?



    Many many thanks!










    share|improve this question



























      1












      1








      1








      I am implementing a LSTM auto-encoder that with the input x and hopefully get the same output as x. However, I have several questions in the implementing, and please see my codes below:



      dict_size = 10
      max_sentence_length = 5
      embed_dim = 20

      x = Input(shape=(max_sentence_length,), dtype='int32')
      encoder_input = Embedding(dict_size, embed_dim)(x)
      encoder_output=LSTM(32, return_sequences=True)(encoder_input)
      deocder_output = LSTM(32, return_sequences=True)(encoder_output)
      y = Dense(dict_size, activation='softmax')(deocder_output)

      model = Model(inputs=x, outputs=y)
      model.compile(optimizer='adam', loss='categorical_crossentropy', metrics=['accuracy'])
      print(model.summary())

      train_x = np.array([[3, 1, 2]])
      train_x = pad_sequences(train_x, max_sentence_length, padding='post')
      train_y = np_utils.to_categorical(train_x, dict_size)

      model.fit(train_x, train_y, batch_size=1, epochs=1)
      predict_y = model.predict(train_x)
      print(predict_y)


      In this codes, the first problem is that : "ValueError: Error when checking target: expected dense_1 to have 3 dimensions, but got array with shape (5, 10)", I really do not know how to solve this problem first.



      The second question is that, the length of x is 3, while with extra padding its length becomes to 5; At the final stage, the output would be a 5x10 matrix, i.e., the last two elements of the final output should not participate into the calculation of the softmax. Is there any way to fix this problem quickly?



      Many many thanks!










      share|improve this question
















      I am implementing a LSTM auto-encoder that with the input x and hopefully get the same output as x. However, I have several questions in the implementing, and please see my codes below:



      dict_size = 10
      max_sentence_length = 5
      embed_dim = 20

      x = Input(shape=(max_sentence_length,), dtype='int32')
      encoder_input = Embedding(dict_size, embed_dim)(x)
      encoder_output=LSTM(32, return_sequences=True)(encoder_input)
      deocder_output = LSTM(32, return_sequences=True)(encoder_output)
      y = Dense(dict_size, activation='softmax')(deocder_output)

      model = Model(inputs=x, outputs=y)
      model.compile(optimizer='adam', loss='categorical_crossentropy', metrics=['accuracy'])
      print(model.summary())

      train_x = np.array([[3, 1, 2]])
      train_x = pad_sequences(train_x, max_sentence_length, padding='post')
      train_y = np_utils.to_categorical(train_x, dict_size)

      model.fit(train_x, train_y, batch_size=1, epochs=1)
      predict_y = model.predict(train_x)
      print(predict_y)


      In this codes, the first problem is that : "ValueError: Error when checking target: expected dense_1 to have 3 dimensions, but got array with shape (5, 10)", I really do not know how to solve this problem first.



      The second question is that, the length of x is 3, while with extra padding its length becomes to 5; At the final stage, the output would be a 5x10 matrix, i.e., the last two elements of the final output should not participate into the calculation of the softmax. Is there any way to fix this problem quickly?



      Many many thanks!







      keras lstm






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Nov 16 '18 at 10:04







      Kevin Sun

















      asked Nov 16 '18 at 9:51









      Kevin SunKevin Sun

      1309




      1309
























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