在阅读了公认的答案后，我感到非常困惑，但这一切都清楚了：

def numbers_to_strings(argument):
    switcher = {
        0: "zero",
        1: "one",
        2: "two",
    }
    return switcher.get(argument, "nothing")

该代码类似于：

function(argument){
    switch(argument) {
        case 0:
            return "zero";
        case 1:
            return "one";
        case 2:
            return "two";
        default:
            return "nothing";
    }
}

有关字典映射到函数的详细信息，请查看源代码。

我做了一个switch-case实现，它在外部不太使用if（它仍然在类中使用if）。

class SwitchCase(object):
    def __init__(self):
        self._cases = dict()

    def add_case(self,value, fn):
        self._cases[value] = fn

    def add_default_case(self,fn):
        self._cases['default']  = fn

    def switch_case(self,value):
        if value in self._cases.keys():
            return self._cases[value](value)
        else:
            return self._cases['default'](0)

这样使用：

from switch_case import SwitchCase
switcher = SwitchCase()
switcher.add_case(1, lambda x:x+1)
switcher.add_case(2, lambda x:x+3)
switcher.add_default_case(lambda _:[1,2,3,4,5])

print switcher.switch_case(1) #2
print switcher.switch_case(2) #5
print switcher.switch_case(123) #[1, 2, 3, 4, 5]

我一直喜欢这样做

result = {
  'a': lambda x: x * 5,
  'b': lambda x: x + 7,
  'c': lambda x: x - 2
}[value](x)

从这里开始

我在谷歌搜索上找不到简单的答案。但我还是想通了。这真的很简单。决定把它贴出来，也许可以防止别人的头上少刮几下。关键是简单的“in”和元组。下面是带有直通的switch语句行为，包括RANDOM直通。

l = ['Dog', 'Cat', 'Bird', 'Bigfoot',
     'Dragonfly', 'Snake', 'Bat', 'Loch Ness Monster']

for x in l:
    if x in ('Dog', 'Cat'):
        x += " has four legs"
    elif x in ('Bat', 'Bird', 'Dragonfly'):
        x += " has wings."
    elif x in ('Snake',):
        x += " has a forked tongue."
    else:
        x += " is a big mystery by default."
    print(x)

print()

for x in range(10):
    if x in (0, 1):
        x = "Values 0 and 1 caught here."
    elif x in (2,):
        x = "Value 2 caught here."
    elif x in (3, 7, 8):
        x = "Values 3, 7, 8 caught here."
    elif x in (4, 6):
        x = "Values 4 and 6 caught here"
    else:
        x = "Values 5 and 9 caught in default."
    print(x)

提供：

Dog has four legs
Cat has four legs
Bird has wings.
Bigfoot is a big mystery by default.
Dragonfly has wings.
Snake has a forked tongue.
Bat has wings.
Loch Ness Monster is a big mystery by default.

Values 0 and 1 caught here.
Values 0 and 1 caught here.
Value 2 caught here.
Values 3, 7, 8 caught here.
Values 4 and 6 caught here
Values 5 and 9 caught in default.
Values 4 and 6 caught here
Values 3, 7, 8 caught here.
Values 3, 7, 8 caught here.
Values 5 and 9 caught in default.

如果您想要默认值，可以使用dictionary get（key[，default]）函数：

def f(x):
    return {
        'a': 1,
        'b': 2
    }.get(x, 9)    # 9 will be returned default if x is not found

我要把我的两分钱放在这里。Python中没有case/switch语句的原因是因为Python遵循“只有一种正确的方法”的原则。很明显，您可以想出各种方法来重新创建switch/case功能，但实现这一点的Python方法是if/elf构造。即。，

if something:
    return "first thing"
elif somethingelse:
    return "second thing"
elif yetanotherthing:
    return "third thing"
else:
    return "default thing"

我只是觉得PEP 8应该在这里获得认可。Python的一个优点是它的简单和优雅。这在很大程度上源于PEP8中提出的原则，包括“只有一种正确的方法可以做某事。”