def f(x):
    dictionary = {'a':1, 'b':2, 'c':3}
    return dictionary.get(x,'Not Found') 
##Returns the value for the letter x;returns 'Not Found' if x isn't a key in the dictionary

Python 3.10（2021）引入了match-case语句，该语句提供了Pythons“switch”的一流实现。例如：

def f(x):
    match x:
        case 'a':
            return 1
        case 'b':
            return 2
        case _:
            return 0   # 0 is the default case if x is not found

match-case语句比这个简单的示例强大得多。

以下原始答案写于2008年，当时还未提供匹配案例：

你可以用字典：

def f(x):
    return {
        'a': 1,
        'b': 2,
    }[x]

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

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

还可以使用列表存储案例，并通过select调用相应的函数-

cases = ['zero()', 'one()', 'two()', 'three()']

def zero():
  print "method for 0 called..."
def one():
  print "method for 1 called..."
def two():
  print "method for 2 called..."
def three():
  print "method for 3 called..."

i = int(raw_input("Enter choice between 0-3 "))

if(i<=len(cases)):
  exec(cases[i])
else:
  print "wrong choice"

也在螺丝台上进行了解释。

class Switch:
    def __init__(self, value):
        self.value = value

    def __enter__(self):
        return self

    def __exit__(self, type, value, traceback):
        return False # Allows a traceback to occur

    def __call__(self, *values):
        return self.value in values


from datetime import datetime

with Switch(datetime.today().weekday()) as case:
    if case(0):
        # Basic usage of switch
        print("I hate mondays so much.")
        # Note there is no break needed here
    elif case(1,2):
        # This switch also supports multiple conditions (in one line)
        print("When is the weekend going to be here?")
    elif case(3,4):
        print("The weekend is near.")
    else:
        # Default would occur here
        print("Let's go have fun!") # Didn't use case for example purposes