def tokenize(train): """ INPUT: Array - Text documents (reviews) to train sentiment on Returns trained tokenizer """ tokenizer = Tokenizer(min_df=10, max_features=100000) print "Training tokenizer on reviews" tokenizer.fit(train) return tokenizer
def train_and_save_passage_tokenizer_and_rnn_model(x_train,
y_train,
x_test,
character_model=False):
"""Train and save Passage tokenizer and Passage RNN model.
x_train and x_test should each be a series that's already been pre-preocessed: html->text, lowercase, removed
punct/#s
x_train+x_test are used to build the tokenizer.
Note that character-based RNN is a work-in-progress and not actuallly implemented as of now.
"""
# Note that we assume we have train/test reviews that had been preprocessed: html->text, lowercased, removed
# punct/#s
# Note in https://github.com/IndicoDataSolutions/Passage/blob/master/examples/sentiment.py they only
# extract text from html, lowercase and strip (no punctuation removal)
# Tokenization: Assign each word in the reviews an ID to be used in all reviews
tokenizer = Tokenizer(min_df=10,
max_features=100000,
character=character_model)
train_reviews_list = x_train.tolist()
tokenizer.fit(train_reviews_list + x_test.tolist())
# Tokenize training reviws (so can use to fit RNN model on)
train_reviews_tokenized = tokenizer.transform(train_reviews_list)
# Based on https://github.com/vinhkhuc/kaggle-sentiment-popcorn/blob/master/scripts/passage_nn.py which is based
# on https://github.com/IndicoDataSolutions/Passage/blob/master/examples/sentiment.py
# RNN Network:
# -Each tokenized review will be converted into a sequence of words, where each word has an embedding representation
# (256)
# -RNN layer (GRU) attempts to find pattern in sequence of words
# -Final dense layer is used as a logistic classifier to turn RNN output into a probability/prediction
if not character_model:
layers = [
Embedding(size=256, n_features=tokenizer.n_features),
# May replace with LstmRecurrent for LSTM layer
GatedRecurrent(size=512,
activation='tanh',
gate_activation='steeper_sigmoid',
init='orthogonal',
seq_output=False,
p_drop=0.75),
Dense(size=1, activation='sigmoid', init='orthogonal')
]
else:
# Character-level RNN
# Idea is to convert character tokenizations into one-hot encodings in which case
# the embeddings layer is no longer needed
train_reviews_tokenized = map(
lambda r_indexes: pd.get_dummies(
r_indexes, columns=range(tokenizer.n_features + 1)).values,
train_reviews_tokenized)
layers = [
# May replace with LstmRecurrent for LSTM layer
GatedRecurrent(size=100,
activation='tanh',
gate_activation='steeper_sigmoid',
init='orthogonal',
seq_output=False,
p_drop=0.75),
Dense(size=1, activation='sigmoid', init='orthogonal')
]
# RNN classifer uses Binary Cross-Entropy as the cost function
classifier = RNN(layers=layers, cost='bce', updater=Adadelta(lr=0.5))
NUM_EPOCHS = 10
# 10 epochs may take 10+ hours to run depending on machine
classifier.fit(train_reviews_tokenized,
y_train.tolist(),
n_epochs=NUM_EPOCHS)
# Store model and tokenizer
if character_model:
passage.utils.save(classifier, PASSAGE_CHAR_RNN_MODEL)
_ = joblib.dump(tokenizer, PASSAGE_CHAR_TOKENIZER, compress=9)
else:
passage.utils.save(classifier, PASSAGE_RNN_MODEL)
_ = joblib.dump(tokenizer, PASSAGE_TOKENIZER, compress=9)
