例子:

>>> convert('CamelCase')
'camel_case'

当前回答

def convert(camel_str):
    temp_list = []
    for letter in camel_str:
        if letter.islower():
            temp_list.append(letter)
        else:
            temp_list.append('_')
            temp_list.append(letter)
    result = "".join(temp_list)
    return result.lower()

其他回答

这不是一个优雅的方法,是一个非常“低级”的实现一个简单的状态机(位域状态机),可能是最反python模式来解决这个问题,然而re模块也实现了一个太复杂的状态机来解决这个简单的任务,所以我认为这是一个很好的解决方案。

def splitSymbol(s):
    si, ci, state = 0, 0, 0 # start_index, current_index 
    '''
        state bits:
        0: no yields
        1: lower yields
        2: lower yields - 1
        4: upper yields
        8: digit yields
        16: other yields
        32 : upper sequence mark
    '''
    for c in s:

        if c.islower():
            if state & 1:
                yield s[si:ci]
                si = ci
            elif state & 2:
                yield s[si:ci - 1]
                si = ci - 1
            state = 4 | 8 | 16
            ci += 1

        elif c.isupper():
            if state & 4:
                yield s[si:ci]
                si = ci
            if state & 32:
                state = 2 | 8 | 16 | 32
            else:
                state = 8 | 16 | 32

            ci += 1

        elif c.isdigit():
            if state & 8:
                yield s[si:ci]
                si = ci
            state = 1 | 4 | 16
            ci += 1

        else:
            if state & 16:
                yield s[si:ci]
            state = 0
            ci += 1  # eat ci
            si = ci   
        print(' : ', c, bin(state))
    if state:
        yield s[si:ci] 


def camelcaseToUnderscore(s):
    return '_'.join(splitSymbol(s)) 

splitsymbol可以解析所有的大小写类型:UpperSEQUENCEInterleaved, under_score, BIG_SYMBOLS和cammelCasedMethods

我希望它是有用的

没有任何库:

def camelify(out):
    return (''.join(["_"+x.lower() if i<len(out)-1 and x.isupper() and out[i+1].islower()
         else x.lower()+"_" if i<len(out)-1 and x.islower() and out[i+1].isupper()
         else x.lower() for i,x in enumerate(list(out))])).lstrip('_').replace('__','_')

有点重,但是

CamelCamelCamelCase ->  camel_camel_camel_case
HTTPRequest         ->  http_request
GetHTTPRequest      ->  get_http_request
getHTTPRequest      ->  get_http_request

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'

在标准库中没有,但我发现这个模块似乎包含您需要的功能。

我也在寻找同样问题的解决方案,只不过我需要一条链子;如。

"CamelCamelCamelCase" -> "Camel-camel-camel-case"

从这两个词的解决方案开始,我想到了以下几点:

"-".join(x.group(1).lower() if x.group(2) is None else x.group(1) \
         for x in re.finditer("((^.[^A-Z]+)|([A-Z][^A-Z]+))", "stringToSplit"))

最复杂的逻辑是避免小写第一个单词。如果你不介意改变第一个词,这里有一个更简单的版本:

"-".join(x.group(1).lower() for x in re.finditer("(^[^A-Z]+|[A-Z][^A-Z]+)", "stringToSplit"))

当然,您可以预先编译正则表达式,或者像其他解决方案中讨论的那样,使用下划线而不是连字符连接正则表达式。