python删除文本中的所有空字符

import re
import os

input_path = 'G:/test/aa.json'
output_path ='G:/test/bb.json'
with open(input_path) as input_file:
    str = input_file.read()
    str = re.sub('\s','',str)
    print str
    with open(output_path, 'w') as output_file:
        output_file.write(str)