I had to do `totalY = np.concatenate( totalY, axis=0 )` before doing `totalY = to_categorical(totalY, nb_classes=11)` https://github.com/erilyth/DeepLearning-Challenges/blob/2750a1c5f008c48f8c6c9c830ae892c399e73467/Sentiment_Analysis/demo.py#L33