python统计单词出现次数

# -*- coding:utf-8 -*-
import io
import re

class Counter:
 def __init__(self, path):
 """
 :param path: 文件路径
 """
 self.mapping = dict()
 with io.open(path, encoding="utf-8") as f:
 data = f.read()
 words = [s.lower() for s in re.findall("w+", data)]
 for word in words:
 self.mapping[word] = self.mapping.get(word, 0) + 1

 def most_common(self, n):
 assert n > 0, "n should be large than 0"
 return sorted(self.mapping.items(), key=lambda item: item[1], reverse=True)[:n]

if __name__ == '__main__':
 most_common_5 = Counter("importthis.txt").most_common(5)
 for item in most_common_5:
 print(item)

('is', 10)
('better', 8)
('than', 8)
('the', 6)
('to', 5)