Switch in Python

There is no switch statement in Python, but there are equivalents depending on what you want to achieve. The best-known use of switch is to evaluate a value and avoid nesting multiple if statements.

Today I will explain it: how to make an equivalent switch in Python.

When you want to evaluate a sentence with multiple conditions

You can observe the most common case when you want to compare the value of an element with multiple conditions.

For example, give the user the option they want, and evaluate depending on it:

menu = """Welcome to the store
1 - New product
2 - See all
3 - Update
4 - Delete
5 - Exit
"""
choose = int(input("Choose an option:"))
switch choose:
	case 1:
		print("Insert")
		break
	case 2:
		print("See")
		break

That is a switch in a universe where Python incorporates it, however, it does not currently exist. Therefore, the code should be as follows:

menu = """Welcome to the store
1 - New product
2 - See all
3 - Update
4 - Delete
5 - Exit
"""
choose = int(input("Choose an option: "))
if choose is 1:
	print("Insert")
elif choose is 2:
	print("See all")
elif choose is 3:
	print("Update")
elif choose is 4:
	print("Delete")
elif choose is 5:
	print("Exit")
else:
	print("Default option here...")

Maybe at the beginning it is a bit cumbersome, but the equivalent to switch in Python are many if statements, with elif (which means else if) and else, which is the default case.

Use switch to get a value

Another use of switch in Python is when you want to get a value of a function from an argument that can have multiple values. For example, get the name of the day from its number; taking Sunday as 0, Monday as 1 and finally Saturday as 6.

For this, the first thing you think is to write a function as follows:

def get_day_name(number_of_day):
	if number_of_day is 0:
		return "Sunday"
	elif number_of_day is 1:
		return "Monday"
	# Here more ifs...
	else:
		return "Unknow"

It’s okay, and it uses the switch equivalent in Python, but it can be written in a better way:

def get_day_name(number_of_day):
	days = {
		0: "Sunday",
		1: "Monday",
		#Here the other days...
	}
	return days.get(number_of_day, "Unknow")

In this way, a dictionary and its get method are used, which receives the key of the value to be obtained (something like the index) and the default value in case the key does not exist.

Conclusion

In conclusion there is no switch statement in Python, but there are equivalents for all cases. In fact, you could say that switch is syntactic sugar for if.