使用正则表达式可能是最短的，但这个解决方案更具可读性:

def to_snake_case(s):
    snake = "".join(["_"+c.lower() if c.isupper() else c for c in s])
    return snake[1:] if snake.startswith("_") else snake

哇，我刚从django片段中偷了这个。ref http://djangosnippets.org/snippets/585/

很优雅

camelcase_to_underscore = lambda str: re.sub(r'(?<=[a-z])[A-Z]|[A-Z](?=[^A-Z])', r'_\g<0>', str).lower().strip('_')

例子:

camelcase_to_underscore('ThisUser')

返回:

'this_user'

REGEX演示

为了好玩:

>>> def un_camel(input):
...     output = [input[0].lower()]
...     for c in input[1:]:
...             if c in ('ABCDEFGHIJKLMNOPQRSTUVWXYZ'):
...                     output.append('_')
...                     output.append(c.lower())
...             else:
...                     output.append(c)
...     return str.join('', output)
...
>>> un_camel("camel_case")
'camel_case'
>>> un_camel("CamelCase")
'camel_case'

或者，更有趣的是:

>>> un_camel = lambda i: i[0].lower() + str.join('', ("_" + c.lower() if c in "ABCDEFGHIJKLMNOPQRSTUVWXYZ" else c for c in i[1:]))
>>> un_camel("camel_case")
'camel_case'
>>> un_camel("CamelCase")
'camel_case'

就我个人而言，我不确定在python中使用正则表达式的任何东西都可以被描述为优雅。这里的大多数答案只是做“代码高尔夫”类型的RE技巧。优雅的编码应该是容易理解的。

def to_snake_case(not_snake_case):
    final = ''
    for i in xrange(len(not_snake_case)):
        item = not_snake_case[i]
        if i < len(not_snake_case) - 1:
            next_char_will_be_underscored = (
                not_snake_case[i+1] == "_" or
                not_snake_case[i+1] == " " or
                not_snake_case[i+1].isupper()
            )
        if (item == " " or item == "_") and next_char_will_be_underscored:
            continue
        elif (item == " " or item == "_"):
            final += "_"
        elif item.isupper():
            final += "_"+item.lower()
        else:
            final += item
    if final[0] == "_":
        final = final[1:]
    return final

>>> to_snake_case("RegularExpressionsAreFunky")
'regular_expressions_are_funky'

>>> to_snake_case("RegularExpressionsAre Funky")
'regular_expressions_are_funky'

>>> to_snake_case("RegularExpressionsAre_Funky")
'regular_expressions_are_funky'

使用:str.capitalize()将字符串(包含在变量str中)的首字母转换为大写字母，并返回整个字符串。

例子: 命令:“你好”.capitalize () 输出:你好

这个网站上提出了非常好的RegEx:

(?<!^)(?=[A-Z])

如果python有一个字符串分割方法，它应该工作…

在Java中:

String s = "loremIpsum";
words = s.split("(?<!^)(?=[A-Z])");