[Tut] Python Set to Tuple | Tuple to Set | 3 Easy Ways

Python Set to Tuple | Tuple to Set | 3 Easy Ways

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Problem Formulation: Given a Python set. How to convert it to a tuple? And how to convert the tuple back to a set?

There are three main ways:

• Method 1: To convert a Python set to a tuple, use the tuple(my_set) function.
• Method 2: To convert a Python tuple to a set, use the set(my_tuple) function.
• Method 3: To convert a Python tuple of mutable elements to a set, use the expression set(tuple(x) for x in my_tuple) to avoid a TypeError.

I’ll also give you a bonus method 4 that shows you what to do to retain the ordering information when converting a tuple to a set—so keep reading!

Method 1: Convert Set to Tuple with tuple()

To convert a set to a tuple, pass the set into the tuple() function. This is a built-in Python function, so you don’t need to import or install any library to use it. The return value is a new tuple from the values in the set.

Here’s an example where you convert the set {1, 2, 3} to a tuple (1, 2, 3):

my_set = {1, 2, 3}

my_tuple = tuple(my_set)

print(my_tuple)

# (1, 2, 3)

By the way, here’s an explainer video on this function:

Method 2: Convert Tuple to Set with set()

To convert a tuple to a set, pass the tuple into the set() function. This is a built-in Python function, so you don’t need to import or install any library. The return value is a new set from the values in the tuple.

Here’s an example where you convert the tuple (1, 2, 3) to a set {1, 2, 3}:

my_tuple = (1, 2, 3)

my_set = set(my_tuple)

print(my_set)

# {1, 2, 3}

Problem: However, the conversion process from a tuple to set doesn’t always work because if you try to convert a tuple of mutable values, Python will raise the TypeError: unhashable type!

Read on to learn more about this problem—and how to resolve it easily:

Method 3: Convert Tuple to Set with Set Comprehension

A Python set is an unordered collection of unique immutable elements. Each element must define explicitly or implicitly the __hash__() dunder method, i.e., must be hashable.

If you attempt to convert a tuple of mutable elements (e.g., lists) to a set, Python will raise an error such as the TypeError: unhashable type: 'list':

my_tuple = ([1, 2], [3, 4], [5, 6])

my_set = set(my_tuple)

# TypeError: unhashable type: 'list'

In this case, you can use set comprehension to convert each inner tuple element to an immutable type. For example, the expression set(tuple(x) for x in my_tuple) converts each inner list to a tuple. The result is a set of immutable tuples.

Here’s the solution to this problem in a minimal code example:

my_tuple = ([1, 2], [3, 4], [5, 6])

my_set = set(tuple(x) for x in my_tuple)

print(my_set)

# {(1, 2), (3, 4), (5, 6)}

The final “bonus” section introduces another elegant way to retain the ordering information in a set:

Bonus Method 4: Enumerate Elements

Sometimes, you want to associate each set or tuple element with a specific numerical “index” value, i.e., a unique integer identifier. The enumerate() method to the rescue!

• Use tuple(enumerate(my_set)) to convert a set to an enumerated tuple.
• Use set(enumerate(my_tuple)) to convert a tuple to an enumerated set.

The result is the respective container data structure with (identifier, value) tuples:

my_set = {'Alice', 'Bob', 'Carl'} my_tuple = tuple(enumerate(my_set))

print(my_tuple)

# ((0, 'Carl'), (1, 'Bob'), (2, 'Alice')) my_set = set(enumerate(('Alice', 'Bob', 'Carl')))

print(my_set)

# {(2, 'Carl'), (0, 'Alice'), (1, 'Bob')}

Especially in the case where you convert a tuple to a set, this makes a lot of sense because you can retain the information on the ordering of elements that would be otherwise lost after converting to a set.

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