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# Copyright 2016 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Example of Estimator for DNN-based text classification with DBpedia data."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
import argparse
import sys
import numpy as np
import pandas
from sklearn import metrics
import tensorflow as tf
FLAGS = None
MAX_DOCUMENT_LENGTH = 10
EMBEDDING_SIZE = 50
n_words = 0
MAX_LABEL = 15
WORDS_FEATURE = 'words' # Name of the input words feature.
def estimator_spec_for_softmax_classification(logits, labels, mode):
"""Returns EstimatorSpec instance for softmax classification."""
predicted_classes = tf.argmax(logits, 1)
if mode == tf.estimator.ModeKeys.PREDICT:
return tf.estimator.EstimatorSpec(
mode=mode,
predictions={
'class': predicted_classes,
'prob': tf.nn.softmax(logits)
})
loss = tf.losses.sparse_softmax_cross_entropy(labels=labels, logits=logits)
if mode == tf.estimator.ModeKeys.TRAIN:
optimizer = tf.train.AdamOptimizer(learning_rate=0.01)
train_op = optimizer.minimize(loss, global_step=tf.train.get_global_step())
return tf.estimator.EstimatorSpec(mode, loss=loss, train_op=train_op)
eval_metric_ops = {
'accuracy':
tf.metrics.accuracy(labels=labels, predictions=predicted_classes)
}
return tf.estimator.EstimatorSpec(
mode=mode, loss=loss, eval_metric_ops=eval_metric_ops)
def bag_of_words_model(features, labels, mode):
"""A bag-of-words model. Note it disregards the word order in the text."""
bow_column = tf.feature_column.categorical_column_with_identity(
WORDS_FEATURE, num_buckets=n_words)
bow_embedding_column = tf.feature_column.embedding_column(
bow_column, dimension=EMBEDDING_SIZE)
bow = tf.feature_column.input_layer(
features, feature_columns=[bow_embedding_column])
logits = tf.layers.dense(bow, MAX_LABEL, activation=None)
return estimator_spec_for_softmax_classification(
logits=logits, labels=labels, mode=mode)
def rnn_model(features, labels, mode):
"""RNN model to predict from sequence of words to a class."""
# Convert indexes of words into embeddings.
# This creates embeddings matrix of [n_words, EMBEDDING_SIZE] and then
# maps word indexes of the sequence into [batch_size, sequence_length,
# EMBEDDING_SIZE].
word_vectors = tf.contrib.layers.embed_sequence(
features[WORDS_FEATURE], vocab_size=n_words, embed_dim=EMBEDDING_SIZE)
# Split into list of embedding per word, while removing doc length dim.
# word_list results to be a list of tensors [batch_size, EMBEDDING_SIZE].
word_list = tf.unstack(word_vectors, axis=1)
# Create a Gated Recurrent Unit cell with hidden size of EMBEDDING_SIZE.
cell = tf.nn.rnn_cell.GRUCell(EMBEDDING_SIZE)
# Create an unrolled Recurrent Neural Networks to length of
# MAX_DOCUMENT_LENGTH and passes word_list as inputs for each unit.
_, encoding = tf.nn.static_rnn(cell, word_list, dtype=tf.float32)
# Given encoding of RNN, take encoding of last step (e.g hidden size of the
# neural network of last step) and pass it as features for softmax
# classification over output classes.
logits = tf.layers.dense(encoding, MAX_LABEL, activation=None)
return estimator_spec_for_softmax_classification(
logits=logits, labels=labels, mode=mode)
def main(unused_argv):
global n_words
tf.logging.set_verbosity(tf.logging.INFO)
# Prepare training and testing data
dbpedia = tf.contrib.learn.datasets.load_dataset(
'dbpedia', test_with_fake_data=FLAGS.test_with_fake_data)
x_train = pandas.Series(dbpedia.train.data[:, 1])
y_train = pandas.Series(dbpedia.train.target)
x_test = pandas.Series(dbpedia.test.data[:, 1])
y_test = pandas.Series(dbpedia.test.target)
# Process vocabulary
vocab_processor = tf.contrib.learn.preprocessing.VocabularyProcessor(
MAX_DOCUMENT_LENGTH)
x_transform_train = vocab_processor.fit_transform(x_train)
x_transform_test = vocab_processor.transform(x_test)
x_train = np.array(list(x_transform_train))
x_test = np.array(list(x_transform_test))
n_words = len(vocab_processor.vocabulary_)
print('Total words: %d' % n_words)
# Build model
# Switch between rnn_model and bag_of_words_model to test different models.
model_fn = rnn_model
if FLAGS.bow_model:
# Subtract 1 because VocabularyProcessor outputs a word-id matrix where word
# ids start from 1 and 0 means 'no word'. But
# categorical_column_with_identity assumes 0-based count and uses -1 for
# missing word.
x_train -= 1
x_test -= 1
model_fn = bag_of_words_model
classifier = tf.estimator.Estimator(model_fn=model_fn)
# Train.
train_input_fn = tf.estimator.inputs.numpy_input_fn(
x={WORDS_FEATURE: x_train},
y=y_train,
batch_size=len(x_train),
num_epochs=None,
shuffle=True)
classifier.train(input_fn=train_input_fn, steps=100)
# Predict.
test_input_fn = tf.estimator.inputs.numpy_input_fn(
x={WORDS_FEATURE: x_test}, y=y_test, num_epochs=1, shuffle=False)
predictions = classifier.predict(input_fn=test_input_fn)
y_predicted = np.array(list(p['class'] for p in predictions))
y_predicted = y_predicted.reshape(np.array(y_test).shape)
# Score with sklearn.
score = metrics.accuracy_score(y_test, y_predicted)
print('Accuracy (sklearn): {0:f}'.format(score))
# Score with tensorflow.
scores = classifier.evaluate(input_fn=test_input_fn)
print('Accuracy (tensorflow): {0:f}'.format(scores['accuracy']))
if __name__ == '__main__':
parser = argparse.ArgumentParser()
parser.add_argument(
'--test_with_fake_data',
default=False,
help='Test the example code with fake data.',
action='store_true')
parser.add_argument(
'--bow_model',
default=False,
help='Run with BOW model instead of RNN.',
action='store_true')
FLAGS, unparsed = parser.parse_known_args()
tf.app.run(main=main, argv=[sys.argv[0]] + unparsed)