如何用Python实现任一个英文的纯文本文件，统计其中的单词出现的个数？

import re

file_name = 'test.txt'

lines_count = 0
words_count = 0
chars_count = 0
words_dict  = {}
lines_list   = []

with open(file_name, 'r') as f:
for line in f:
lines_count = lines_count + 1
chars_count  = chars_count + len(line)
match = re.findall(r'[^a-zA-Z0-9]+', line)
for i in match:
# 只要英文单词，删掉其他字符
line = line.replace(i, ' ')
lines_list = line.split()
for i in lines_list:
if i not in words_dict:
words_dict[i] = 1
else:
words_dict[i] = words_dict[i] + 1

print 'words_count is', len(words_dict)
print 'lines_count is', lines_count
print 'chars_count is', chars_count

for k,v in words_dict.items():
print k,v