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preprocessing.py
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preprocessing.py
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import csv
import numpy as np
import string as str
from datetime import datetime
from pprint import pprint
from itertools import islice
from nltk.tokenize import word_tokenize
from nltk.stem.snowball import SnowballStemmer
from sklearn.feature_extraction.text import CountVectorizer
from sklearn.feature_extraction.text import TfidfVectorizer
from gensim.models.word2vec import Word2Vec
__author__ = 'miljan'
def read_data():
with open('./data/tweets.tsv', 'rU') as file1:
# filter removes the rows starting with # (comments)
file_reader = csv.reader(filter(lambda x: x[0] in str.digits, file1), delimiter='\t', dialect=csv.excel_tab)
# matrix containing all 8 ranking for each tweet
rating_matrix = []
data_matrix = []
for row in file_reader:
data_matrix.append([row[0]] + [process_timestamp(row[1])] + row[2:5])
rating_matrix.append(row[5:])
# first pad each array with 0 until the end, and then also replace any '' with 0
rating_matrix = [[x if x is not '' else '0' for x in y + ['0']*(8 - len(y))] for y in rating_matrix]
# convert to numpy ints
rating_matrix = np.array(rating_matrix, dtype='int')
return data_matrix, rating_matrix
def argmax(arr):
max_element = max(arr)
i = 0
arg_maxes = []
for element in arr:
if element == max_element:
arg_maxes.append(i)
i += 1
# return the least confident result
return arg_maxes[-1]
def process_timestamp(timestamp):
return datetime.strptime(timestamp, '%m/%d/%y %H:%M')
def list_of_ints_from_string(s):
l = []
for t in word_tokenize(s.decode("utf8")):
try:
l.append(int(float(t)))
except ValueError:
pass
return l
def cleaned_bag_of_words_dataset(data_matrix, stemming=False, stop_words=None, TFIDF=False, ngram_range=(1, 1), max_features=None,
length=False, number_in_tweet=False, words_present=[]):
if stemming:
stemmer = SnowballStemmer("english")
tweets = [" ".join([stemmer.stem(word) for word in word_tokenize(data_point[2].lower().decode("utf8"))]) for data_point in data_matrix]
else:
tweets = [data_point[2].lower() for data_point in data_matrix]
if TFIDF:
vectorizer = TfidfVectorizer(stop_words=stop_words, ngram_range=ngram_range, max_features=max_features)
else:
vectorizer = CountVectorizer(stop_words=stop_words, ngram_range=ngram_range, max_features=max_features)
dataset = vectorizer.fit_transform(tweets).toarray()
if length:
lengths = np.array([[len(word_tokenize(data_point[2].decode("utf8")))] for data_point in data_matrix])
dataset = np.concatenate((dataset, lengths), axis=1)
if number_in_tweet:
numbers = []
for data_point in data_matrix:
number_list = list_of_ints_from_string(data_point[2])
filtered_number_list = [number for number in number_list if abs(number) < 10]
if len(filtered_number_list) == 0:
numbers.append([0])
else:
numbers.append([np.mean(filtered_number_list)])
dataset = np.concatenate((dataset, numbers), axis=1)
for word in words_present:
word_present = np.array([[int(word.lower() in word_tokenize(data_point[2].lower().decode("utf8")))] for data_point in data_matrix])
dataset = np.concatenate((dataset, word_present), axis=1)
return dataset
# derive sentence representation have sum of word vectors
def _build_sent_vec_as_sum(clean_sent, model):
temp = np.zeros((1, 300))
for word in clean_sent:
try:
temp += model[word]
except:
pass
return temp
# derive sentence representation as average of word vectors
def _build_sent_vec_as_average(clean_sent, model):
temp = np.zeros((1, 300))
count = 0
for word in clean_sent:
try:
temp += model[word]
count += 1
except:
pass
return temp/count if count > 0 else temp
def word2vec_features(data_matrix, stemming=False, stop_words=None, TFIDF=False, ngram_range=(1, 1), max_features=None,
length=False, number_in_tweet=False, words_present=[], policy='sum'):
print '\n------------------'
print 'Creating feature vector matrix...\n'
if stemming:
print '\n------------------'
print 'Stemming...'
stemmer = SnowballStemmer("english")
tweets = [" ".join([stemmer.stem(word) for word in word_tokenize(data_point[2].lower().decode("utf8"))]) for data_point in data_matrix]
else:
tweets = [data_point[2].lower() for data_point in data_matrix]
print '\n------------------'
print 'Loading word2vec model...'
model = Word2Vec.load_word2vec_format('./data/GoogleNews-vectors-negative300.bin', binary=True) # C binary format
# determine the policy on how to build vectors
if policy == 'sum':
policy = _build_sent_vec_as_sum
else:
policy = _build_sent_vec_as_average
print 'Applying word2vec model...'
# create a len(tweets) x 300 dimensional matrix
dataset = np.squeeze(np.array([policy(sent, model) for sent in tweets]))
print "Done"
if length:
lengths = np.array([[len(word_tokenize(data_point[2].decode("utf8")))] for data_point in data_matrix])
dataset = np.concatenate((dataset, lengths), axis=1)
if number_in_tweet:
numbers = []
for data_point in data_matrix:
number_list = list_of_ints_from_string(data_point[2])
filtered_number_list = [number for number in number_list if abs(number) < 10]
if len(filtered_number_list) == 0:
numbers.append([0])
else:
numbers.append([np.mean(filtered_number_list)])
dataset = np.concatenate((dataset, numbers), axis=1)
for word in words_present:
word_present = np.array([[int(word.lower() in word_tokenize(data_point[2].lower().decode("utf8")))] for data_point in data_matrix])
dataset = np.concatenate((dataset, word_present), axis=1)
print '\n------------------'
print 'Feature vector constructed.'
return dataset
def majority_voting_ratings(rating_matrix):
majority_rating = []
for ratings in rating_matrix:
majority_rating.append(argmax(np.bincount(ratings)[1:]))
return np.array(majority_rating)
def convert_4_to_3(x):
if x == 4:
return 3
return x
def majority_voting_ratings_merge_3_4(rating_matrix):
majority_rating = []
for ratings in rating_matrix:
ratings = map(convert_4_to_3, ratings)
majority_rating.append(argmax(np.bincount(ratings)[1:]))
return np.array(majority_rating)
if __name__ == '__main__':
data_matrix, rating_matrix = read_data()