def demo_subjectivity(trainer, save_analyzer=False, n_instances=None, output=None):
"""
Train and test a classifier on instances of the Subjective Dataset by Pang and
Lee. The dataset is made of 5000 subjective and 5000 objective sentences.
All tokens (words and punctuation marks) are separated by a whitespace, so
we use the basic WhitespaceTokenizer to parse the data.
:param trainer: `train` method of a classifier.
:param save_analyzer: if `True`, store the SentimentAnalyzer in a pickle file.
:param n_instances: the number of total sentences that have to be used for
training and testing. Sentences will be equally split between positive
and negative.
:param output: the output file where results have to be reported.
"""
from sentiment_analyzer import SentimentAnalyzer
from nltk.corpus import subjectivity
if n_instances is not None:
n_instances = int(n_instances/2)
subj_docs = [(sent, 'subj') for sent in subjectivity.sents(categories='subj')[:n_instances]]
obj_docs = [(sent, 'obj') for sent in subjectivity.sents(categories='obj')[:n_instances]]
# We separately split subjective and objective instances to keep a balanced
# uniform class distribution in both train and test sets.
train_subj_docs, test_subj_docs = split_train_test(subj_docs)
train_obj_docs, test_obj_docs = split_train_test(obj_docs)
training_docs = train_subj_docs+train_obj_docs
testing_docs = test_subj_docs+test_obj_docs
sentim_analyzer = SentimentAnalyzer()
all_words_neg = sentim_analyzer.all_words([mark_negation(doc) for doc in training_docs])
# Add simple unigram word features handling negation
unigram_feats = sentim_analyzer.unigram_word_feats(all_words_neg, min_freq=4)
sentim_analyzer.add_feat_extractor(extract_unigram_feats, unigrams=unigram_feats)
# Apply features to obtain a feature-value representation of our datasets
training_set = sentim_analyzer.apply_features(training_docs)
test_set = sentim_analyzer.apply_features(testing_docs)
classifier = sentim_analyzer.train(trainer, training_set)
try:
classifier.show_most_informative_features()
except AttributeError:
print('Your classifier does not provide a show_most_informative_features() method.')
results = sentim_analyzer.evaluate(test_set)
if save_analyzer == True:
save_file(sentim_analyzer, 'sa_subjectivity.pickle')
if output:
extr = [f.__name__ for f in sentim_analyzer.feat_extractors]
output_markdown(output, Dataset='subjectivity', Classifier=type(classifier).__name__,
Tokenizer='WhitespaceTokenizer', Feats=extr,
Instances=n_instances, Results=results)
return sentim_analyzer
class Utility:
def __init__(self):
self.sentiment = SentimentAnalyzer()
self.clf = self.sentiment.clf
def classifiersVsFeatures(self):
with open('pickled/features_train.pickle', 'rb') as features_train:
X_train = pickle.load(features_train)
with open('pickled/features_test.pickle', 'rb') as features_test:
X_test = pickle.load(features_test)
with open('pickled/labels_train.pickle', 'rb') as labels_train:
y_train = pickle.load(labels_train)
with open('pickled/labels_test.pickle', 'rb') as labels_test:
y_test = pickle.load(labels_test)
num_features = [10000, 50000, 100000, 500000, 1000000]
acc = []
for i in range(0, len(self.clf)):
acc.append([])
for k in num_features:
pipeline, model = self.sentiment.trainData(X_train, y_train,
self.clf, k)
prediction = self.sentiment.predictData(X_test, model)
clf_metrics = self.sentiment.evaluate(y_test, prediction)
for j in range(0, len(self.clf)):
print(clf_metrics[0][j])
acc[j].append(
clf_metrics[0]
[j]) # Append the accuracy of the classifier for each k
data = []
for i in range(0, len(self.clf)):
data.append({'x': num_features, 'y': acc[i]})
return data
def showTopFeatures(self, pipeline, n=20):
vectorizer = pipeline.named_steps['vect']
clf = pipeline.named_steps['clf']
feature_names = vectorizer.get_feature_names()
coefs = sorted(zip(clf.coef_[0], feature_names), reverse=True)
topn = zip(coefs[:n], coefs[:-(n + 1):-1])
top_features = []
for (coef_p, feature_p), (coef_n, feature_n) in topn:
top_features.append('{:0.4f}{: >25} {:0.4f}{: >25}'.format(
coef_p, feature_p, coef_n, feature_n))
return '\n'.join(top_features)
def demo_movie_reviews(trainer, n_instances=None, output=None):
"""
Train classifier on all instances of the Movie Reviews dataset.
The corpus has been preprocessed using the default sentence tokenizer and
WordPunctTokenizer.
Features are composed of:
- most frequent unigrams
:param trainer: `train` method of a classifier.
:param n_instances: the number of total reviews that have to be used for
training and testing. Reviews will be equally split between positive and
negative.
:param output: the output file where results have to be reported.
"""
from nltk.corpus import movie_reviews
from sentiment_analyzer import SentimentAnalyzer
if n_instances is not None:
n_instances = int(n_instances/2)
pos_docs = [(list(movie_reviews.words(pos_id)), 'pos') for pos_id in movie_reviews.fileids('pos')[:n_instances]]
neg_docs = [(list(movie_reviews.words(neg_id)), 'neg') for neg_id in movie_reviews.fileids('neg')[:n_instances]]
# We separately split positive and negative instances to keep a balanced
# uniform class distribution in both train and test sets.
train_pos_docs, test_pos_docs = split_train_test(pos_docs)
train_neg_docs, test_neg_docs = split_train_test(neg_docs)
training_docs = train_pos_docs+train_neg_docs
testing_docs = test_pos_docs+test_neg_docs
sentim_analyzer = SentimentAnalyzer()
all_words = sentim_analyzer.all_words(training_docs)
# Add simple unigram word features
unigram_feats = sentim_analyzer.unigram_word_feats(all_words, min_freq=4)
sentim_analyzer.add_feat_extractor(extract_unigram_feats, unigrams=unigram_feats)
# Apply features to obtain a feature-value representation of our datasets
training_set = sentim_analyzer.apply_features(training_docs)
test_set = sentim_analyzer.apply_features(testing_docs)
classifier = sentim_analyzer.train(trainer, training_set)
try:
classifier.show_most_informative_features()
except AttributeError:
print('Your classifier does not provide a show_most_informative_features() method.')
results = sentim_analyzer.evaluate(test_set)
if output:
extr = [f.__name__ for f in sentim_analyzer.feat_extractors]
output_markdown(output, Dataset='Movie_reviews', Classifier=type(classifier).__name__,
Tokenizer='WordPunctTokenizer', Feats=extr, Results=results,
Instances=n_instances)
def demo_tweets(trainer, n_instances=None, output=None):
"""
Train and test Naive Bayes classifier on 10000 tweets, tokenized using
TweetTokenizer.
Features are composed of:
- 1000 most frequent unigrams
- 100 top bigrams (using BigramAssocMeasures.pmi)
:param trainer: `train` method of a classifier.
:param n_instances: the number of total tweets that have to be used for
training and testing. Tweets will be equally split between positive and
negative.
:param output: the output file where results have to be reported.
"""
from nltk.tokenize import TweetTokenizer
from sentiment_analyzer import SentimentAnalyzer
from nltk.corpus import twitter_samples, stopwords
# Different customizations for the TweetTokenizer
tokenizer = TweetTokenizer(preserve_case=False)
# tokenizer = TweetTokenizer(preserve_case=True, strip_handles=True)
# tokenizer = TweetTokenizer(reduce_len=True, strip_handles=True)
if n_instances is not None:
n_instances = int(n_instances/2)
fields = ['id', 'text']
positive_json = twitter_samples.abspath("positive_tweets.json")
positive_csv = 'positive_tweets.csv'
json2csv_preprocess(positive_json, positive_csv, fields, limit=n_instances)
negative_json = twitter_samples.abspath("negative_tweets.json")
negative_csv = 'negative_tweets.csv'
json2csv_preprocess(negative_json, negative_csv, fields, limit=n_instances)
neg_docs = parse_tweets_set(negative_csv, label='neg', word_tokenizer=tokenizer)
pos_docs = parse_tweets_set(positive_csv, label='pos', word_tokenizer=tokenizer)
# We separately split subjective and objective instances to keep a balanced
# uniform class distribution in both train and test sets.
train_pos_docs, test_pos_docs = split_train_test(pos_docs)
train_neg_docs, test_neg_docs = split_train_test(neg_docs)
training_tweets = train_pos_docs+train_neg_docs
testing_tweets = test_pos_docs+test_neg_docs
sentim_analyzer = SentimentAnalyzer()
# stopwords = stopwords.words('english')
# all_words = [word for word in sentim_analyzer.all_words(training_tweets) if word.lower() not in stopwords]
all_words = [word for word in sentim_analyzer.all_words(training_tweets)]
# Add simple unigram word features
unigram_feats = sentim_analyzer.unigram_word_feats(all_words, top_n=1000)
sentim_analyzer.add_feat_extractor(extract_unigram_feats, unigrams=unigram_feats)
# Add bigram collocation features
bigram_collocs_feats = sentim_analyzer.bigram_collocation_feats([tweet[0] for tweet in training_tweets],
top_n=100, min_freq=12)
sentim_analyzer.add_feat_extractor(extract_bigram_feats, bigrams=bigram_collocs_feats)
training_set = sentim_analyzer.apply_features(training_tweets)
test_set = sentim_analyzer.apply_features(testing_tweets)
classifier = sentim_analyzer.train(trainer, training_set)
# classifier = sentim_analyzer.train(trainer, training_set, max_iter=4)
try:
classifier.show_most_informative_features()
except AttributeError:
print('Your classifier does not provide a show_most_informative_features() method.')
results = sentim_analyzer.evaluate(test_set)
if output:
extr = [f.__name__ for f in sentim_analyzer.feat_extractors]
output_markdown(output, Dataset='labeled_tweets', Classifier=type(classifier).__name__,
Tokenizer=tokenizer.__class__.__name__, Feats=extr,
Results=results, Instances=n_instances)
