How to convert a Python set to a string

Sometimes, you may need to convert a set object to a string object in Python.

By default, Python allows you to convert a set object to a string using the str() function as follows:

my_set = {"A", "S", "D"}

my_str = str(my_set)

print(my_str)

But the result will be a string with curly brackets as shown below:

{'S', 'D', 'A'}

Most likely, you want to improve the conversion and remove the curly brackets, the extra quotation mark, and the commas.

There are two methods you can use to better convert a set to a string in Python:

1. Using the str.join() method
2. Using a for loop

In this tutorial, I will show you how to use both methods in practice.

Convert set to string with the str.join() method

Since a set is an iterable object, you can use the str.join() method to join the items in the set as a string.

You can call the join() method from an empty string as follows:

my_set = {"A", "S", "D"}

my_str = "".join(my_set)

print(my_str)

Output:

ASD

If you want to add some character between the elements, you can specify the character in the string from which you call the join() method:

my_set = {"A", "S", "D"}

my_str = "-".join(my_set)

print(my_str) 

Output:

A-S-D

Keep in mind that a set is an unordered data structure, so the insertion order is not preserved. This is why the string has a different order than the set you defined.

One weakness of this method is that if you have a set of mixed types, then the join() method will raise an error.

Suppose you have a mixed set as shown below:

my_set = {"A", 1, 2, True, "B"}

my_str = "".join(my_set)

print(my_str)

Output:

Traceback (most recent call last):
  File "main.py", line 3, in <module>
    my_str = "".join(my_set)
             ^^^^^^^^^^^^^^^
TypeError: sequence item 0: expected str instance, int found

See how the join() method expected a str instance, but int is found instead.

To overcome this limitation, you need to use a for loop as explained below.

2. Using a for loop

To convert a set to a string, you can also use a for loop to iterate over the set and assign each value to a string. Here’s an example:

my_set = {"A", 1, 2.4, "B"}

my_str = ""

for item in my_set:
    my_str = my_str + str(item)

print(my_str)

Output:

B2.4A1

One benefit of using this method is that you can convert a set of mixed types to a string by calling the str() function on each item.

This way, you can convert a set of strings, integers, or floats just fine.

Conclusion

Now you’ve learned how to convert a set to a string in Python. Happy coding! 👍