Sample Program

python -m nltk.downloader stopwords
python -m nltk.downloader punkt

To run, use the following command:

python Summarizer.py <filename> -l <length of expected summary>

Summarizer.py

@@ -0,0 +1,70 @@
+import argparse
+
+from nltk.tokenize import sent_tokenize, word_tokenize
+from nltk.corpus import stopwords
+from string import punctuation
+from nltk.probability import FreqDist
+from heapq import nlargest
+from collections import defaultdict
+
+def main():
+	args = parse_arguments()
+	content = read_file(args.filepath)
+	content = sanitize_input(content)
+
+	sent_tokens, word_tokens = tokenize_content(content)
+	sent_ranks = score_tokens(sent_tokens, word_tokens)
+	print(summarize(sent_ranks, sent_tokens, args.length))
+
+def parse_arguments():
+	parser = argparse.ArgumentParser()
+	parser.add_argument('filepath', help='File name of text to summarize')
+	parser.add_argument('-l', '--length', default=4, help='No. of sentences to return')
+	args = parser.parse_args()
+	return args
+
+def read_file(path):
+	try:
+		with open(path, 'r') as f:
+			return f.read()
+	except IOError as e:
+		print('File could not be located')
+
+def sanitize_input(data):
+	replace = {
+		ord('\f') : ' ',
+		ord('\t') : ' ',
+		ord('\n') : ' ',
+		ord('\r') : None
+	}
+	return data.translate(replace)
+
+def tokenize_content(content):
+
+	stop_words = set(stopwords.words('english') + list(punctuation))
+	words = word_tokenize(content.lower())
+	return (sent_tokenize(content), [word for word in words if word not in stop_words])
+
+def score_tokens(sent_tokens, word_tokens):
+	word_freq = FreqDist(word_tokens)
+	rank = defaultdict(int)
+	for i, sent in enumerate(sent_tokens):
+		for  word in word_tokenize(sent.lower()):
+			if word in word_freq:
+				rank[i] += word_freq[word]
+
+	return rank
+
+def summarize(ranks, sentences, length):
+
+	if int(length) > len(sentences):
+		print('You requested more sentences in the summary than there are in the text.')
+		return ''
+
+	else:
+		indices = nlargest(int(length), ranks, key=ranks.get)
+		final_summary = [sentences[j] for j in indices]
+		return ' '.join(final_summary)
+
+if __name__ == '__main__':
+  main()