Python格式化千分位数字

Python 2.7及以上版本直接使用format设置千分位分隔符

Python 2.7.14 (v2.7.14:84471935ed, Sep 16 2017, 20:25:58) [MSC v.1500 64 bit (AMD64)] on win32
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>>> format(1234567890, ',')
'1,234,567,890'
>>>

正则实现

import re
def number_format(s):
    s = str(s)
    while True:
        (s, count) = re.subn(r"(\d)(\d{3})((:?,\d\d\d)*)$", r"\1,\2\3", s)
        if count == 0 : break
    return s
print number_format(1234567890)