就我个人而言，我尝试在类、mixedCase方法和函数中使用CamelCase。变量通常用下划线分隔(当我记得的时候)。这样我一眼就能知道我到底在调用什么，而不是所有东西看起来都一样。

如前所述，PEP 8要求对变量、方法和函数使用lower_case_with_下划线。

我更喜欢使用lower_case_with_下划线的变量和mixedCase的方法和函数，使代码更显式和可读。因此，遵循Python的“显式优于隐式”和“可读性很重要”的禅意。

大多数使用python的人更喜欢下划线，但即使我已经使用python 5年多了，我仍然不喜欢它们。我只是觉得它们很丑，但也许这就是我脑子里的爪哇。

I simply like CamelCase better since it fits better with the way classes are named, It feels more logical to have SomeClass.doSomething() than SomeClass.do_something(). If you look around in the global module index in python, you will find both, which is due to the fact that it's a collection of libraries from various sources that grew overtime and not something that was developed by one company like Sun with strict coding rules. I would say the bottom line is: Use whatever you like better, it's just a question of personal taste.

无论是否在课堂上或在课堂外:

变量和函数小写，如下所示:

name = "John"

def display(name):
    print("John")

如果它们多于一个单词，则用下划线“_”分隔，如下所示:

first_name = "John"

def display_first_name(first_name):
    print(first_name)

并且，如果一个变量是一个常量，它是大写的，如下所示:

FIRST_NAME = "John"

There is PEP 8, as other answers show, but PEP 8 is only the styleguide for the standard library, and it's only taken as gospel therein. One of the most frequent deviations of PEP 8 for other pieces of code is the variable naming, specifically for methods. There is no single predominate style, although considering the volume of code that uses mixedCase, if one were to make a strict census one would probably end up with a version of PEP 8 with mixedCase. There is little other deviation from PEP 8 that is quite as common.

有一篇关于这方面的论文:http://www.cs.kent.edu/~jmaletic/papers/ICPC2010-CamelCaseUnderScoreClouds.pdf

它说snake_case比camelCase可读性更好。这就是为什么现代语言在任何可能的地方都使用(或应该使用)蛇。