Replacements for switch statement in Python

Question

If i have to write a function in Python that returns different fixed values based on the value of an input index.

In other languages I would use a switch or case statement, but Python does not appear to have a switch statement. What are the recommended Python solutions?

Answer 1

If you'd like defaults you could use the dictionary get(key[, default]) method:

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

This would help.

Answer 2

The recommended path for Python 3.10 which is for 2021 which was  introduced with the match-case statement which will give access to a first-class implementation of a "switch" for Python. The example below should help you with clarity:

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

The match-case statement is considerably more powerful than this simple example. You could also try using a dictionary:
 

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