避免使用库和正则表达式:

def camel_to_snake(s):
    return ''.join(['_'+c.lower() if c.isupper() else c for c in s]).lstrip('_')

>>> camel_to_snake('ThisIsMyString')
'this_is_my_string'

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

Stringcase是我的首选库;例如:

>>> from stringcase import pascalcase, snakecase
>>> snakecase('FooBarBaz')
'foo_bar_baz'
>>> pascalcase('foo_bar_baz')
'FooBarBaz'

一个使用正则表达式的可怕例子(你可以很容易地清理:)):

def f(s):
    return s.group(1).lower() + "_" + s.group(2).lower()

p = re.compile("([A-Z]+[a-z]+)([A-Z]?)")
print p.sub(f, "CamelCase")
print p.sub(f, "getHTTPResponseCode")

但适用于getHTTPResponseCode !

或者，使用lambda:

p = re.compile("([A-Z]+[a-z]+)([A-Z]?)")
print p.sub(lambda x: x.group(1).lower() + "_" + x.group(2).lower(), "CamelCase")
print p.sub(lambda x: x.group(1).lower() + "_" + x.group(2).lower(), "getHTTPResponseCode")

编辑:对于像“Test”这样的情况，应该也很容易看到有改进的空间，因为下划线是无条件插入的。

看一看优秀的Schematics库

https://github.com/schematics/schematics

它允许你创建类型化的数据结构，可以序列化/反序列化从python到Javascript风格，例如:

class MapPrice(Model):
    price_before_vat = DecimalType(serialized_name='priceBeforeVat')
    vat_rate = DecimalType(serialized_name='vatRate')
    vat = DecimalType()
    total_price = DecimalType(serialized_name='totalPrice')

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])");