骆驼案变蛇案

import re

name = 'CamelCaseName'
name = re.sub(r'(?<!^)(?=[A-Z])', '_', name).lower()
print(name)  # camel_case_name

如果你这样做了很多次，上面的速度很慢，提前编译正则表达式:

pattern = re.compile(r'(?<!^)(?=[A-Z])')
name = pattern.sub('_', name).lower()

为了处理更高级的情况(这是不可逆的了):

def camel_to_snake(name):
    name = re.sub('(.)([A-Z][a-z]+)', r'\1_\2', name)
    return re.sub('([a-z0-9])([A-Z])', r'\1_\2', name).lower()

print(camel_to_snake('camel2_camel2_case'))  # camel2_camel2_case
print(camel_to_snake('getHTTPResponseCode'))  # get_http_response_code
print(camel_to_snake('HTTPResponseCodeXYZ'))  # http_response_code_xyz

添加带有两个或两个以上下划线的also大小写:

def to_snake_case(name):
    name = re.sub('(.)([A-Z][a-z]+)', r'\1_\2', name)
    name = re.sub('__([A-Z])', r'_\1', name)
    name = re.sub('([a-z0-9])([A-Z])', r'\1_\2', name)
    return name.lower()

斯内克案转帕斯卡案

name = 'snake_case_name'
name = ''.join(word.title() for word in name.split('_'))
print(name)  # SnakeCaseName

骆驼案变蛇案

import re

name = 'CamelCaseName'
name = re.sub(r'(?<!^)(?=[A-Z])', '_', name).lower()
print(name)  # camel_case_name

如果你这样做了很多次，上面的速度很慢，提前编译正则表达式:

pattern = re.compile(r'(?<!^)(?=[A-Z])')
name = pattern.sub('_', name).lower()

为了处理更高级的情况(这是不可逆的了):

def camel_to_snake(name):
    name = re.sub('(.)([A-Z][a-z]+)', r'\1_\2', name)
    return re.sub('([a-z0-9])([A-Z])', r'\1_\2', name).lower()

print(camel_to_snake('camel2_camel2_case'))  # camel2_camel2_case
print(camel_to_snake('getHTTPResponseCode'))  # get_http_response_code
print(camel_to_snake('HTTPResponseCodeXYZ'))  # http_response_code_xyz

添加带有两个或两个以上下划线的also大小写:

def to_snake_case(name):
    name = re.sub('(.)([A-Z][a-z]+)', r'\1_\2', name)
    name = re.sub('__([A-Z])', r'_\1', name)
    name = re.sub('([a-z0-9])([A-Z])', r'\1_\2', name)
    return name.lower()

斯内克案转帕斯卡案

name = 'snake_case_name'
name = ''.join(word.title() for word in name.split('_'))
print(name)  # SnakeCaseName

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

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

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。

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