Python nltk.trigrams() Examples

def test():
    lm1 = pickle.load(open("lm.bin", 'rb'))

    tweets_list = deviger.load_dataset('test.txt')

    for line in tweets_list:
        sentences = nltk.sent_tokenize(line.strip())
        print("Tweet sentences:", sentences)
        for sent in sentences:
            words = nltk.word_tokenize(sent)
            word_trigrams = nltk.trigrams(words)
                sum_log_prob = 0
            for trigram in word_trigrams:
                logprob = lm1.log_prob(trigram)
                sum_log_prob += logprob
            print("(", sum_log_prob / len(words), ")") 

def train_trigram(lst):
    model = defaultdict(lambda: defaultdict(lambda: 0))
    for sent in lst:
        sent = sent.split()
        for w1, w2, w3 in trigrams(sent, pad_right=True, pad_left=True):
            model[(w1,w2)][w2] += 1
    total_count = 0
    for w1,w2 in model:
        total_count = float(sum(model[(w1, w2)].values()))
        for w3 in model[(w1,w2)]:
            model[(w1, w2)][w3] /= total_count

#Total Sum Of Trigram Probablity Of A Sentence[Returns Float]: 

def trigram_counts(word_list):
	tgs = nltk.trigrams(word_list)
	fdist = nltk.FreqDist(tgs)
	d = Counter()
	for k, v in fdist.items():
		d[k] = v
	return d 

def train_trigram(lst):
    model = defaultdict(lambda: defaultdict(lambda: 0))
    for sent in lst:
        sent = sent.split()
        for w1, w2, w3 in trigrams(sent, pad_right=True, pad_left=True):
            model[(w1,w2)][w2] += 1
    total_count = 0
    for w1,w2 in model:
        total_count = float(sum(model[(w1, w2)].values()))
        for w3 in model[(w1,w2)]:
            model[(w1, w2)][w3] /= total_count

#Total Sum Of Trigram Probablity Of A Sentence[Returns Float]: 

def tokenize(text):
      # text = NB.remove_punctuation(text)
      try:
        text = text.decode('utf-8').encode('ascii', 'replace').strip().lower()
      except:
        text = text.encode('ascii', 'replace').strip().lower()
      word = [porter.stem(w) for w in re.findall(r"[\w'-]+|[^\s\w]", text)]   # split punctuations but dont split single quotes for words like don't
      biword =  [b for b in nltk.bigrams(word)]
      triword =  [t for t in nltk.trigrams(word)]
      # word = [w for w in word if w not in stopwords.words('english')]
      return  word # triword 

def get_collocations(words):
	# returns n-grams up to trigrams that appear at least 3 times, with pruning of grams that are redundant
	minimum_frequency = 3
	ngrams = {"_".join(ngram): frequency/len(words) for ngram, frequency in FreqDist(everygrams(words, max_len=3)).items() if frequency > minimum_frequency}
	collocations = dict(ngrams)
	for ngram, likelihood in dict(ngrams).iteritems():
		grams = ngram.split("_")
		if len(grams) != 1:
			gram_likelihoods = [ngrams[gram] for gram in grams]
			if likelihood < 0.5 * np.prod(gram_likelihoods)**(1 / len(grams)):
				collocations.pop(ngram, None)
			else:
				for gram in grams:
					collocations.pop(gram, None)
	return sorted(collocations.items(), key=itemgetter(1), reverse=True) 

def create_qb_tokenizer(
        unigrams=True, bigrams=False, trigrams=False,
        zero_length_token='zerolengthunk', strip_qb_patterns=True):
    def tokenizer(text):
        if strip_qb_patterns:
            text = re.sub(
                '\s+', ' ',
                re.sub(regex_pattern, ' ', text, flags=re.IGNORECASE)
            ).strip().capitalize()
        import nltk
        tokens = nltk.word_tokenize(text)
        if len(tokens) == 0:
            return [zero_length_token]
        else:
            ngrams = []
            if unigrams:
                ngrams.extend(tokens)
            if bigrams:
                ngrams.extend([f'{w0}++{w1}' for w0, w1 in nltk.bigrams(tokens)])
            if trigrams:
                ngrams.extend([f'{w0}++{w1}++{w2}' for w0, w1, w2 in nltk.trigrams(tokens)])

            if len(ngrams) == 0:
                ngrams.append(zero_length_token)
            return ngrams

    return tokenizer