How to check if an object is iterable in Python

An iterable object is any object that can be iterated over using a for loop. Some examples of iterable objects in Python are strings, lists, and tuples.

When developing with Python, you may get a variable or custom object, but you don’t know if it’s iterable or not.

Knowing if a given object is iterable or not is important because Python will raise a TypeError when you try to iterate over a non-iterable object.

In this article, you will learn different ways to check if an object is iterable in Python.

1. Using the iter() function

The iter() function takes an object as an argument and returns an iterator object if the object is iterable.

Under the hood, the iter() function checks if the object has __iter__() or __getitem__() method implemented. If not, the function will return a TypeError.

You need to wrap the call to this function in a try-except block as follows:

list = [1, 2, 3]

try:
    iterable = iter(list)
    print("The object is iterable")
except TypeError:
    print("The object is not iterable")

Since the list object is iterable, Python won’t execute the except block.

2. Using the isinstance() function

You can also use the isinstance() function together with the Iterable class to check if an object is iterable or not.

This function takes two parameters: an object and a type.

The function returns True if the object is an instance of the given type. Otherwise, it returns False.

Here’s an example of using the isinstance() function to check if a string is an instance of the Iterable class:

from collections.abc import Iterable

my_string = "Nathan"

is_iterable = isinstance(my_string, Iterable)

print(is_iterable)  # True

Note that you need to import the Iterable class from the collections.abc module.

Also, this solution is less preferred than the iter() function because the Iterable class only checks for the modern __iter__() method while ignoring the existence of the __getitem__() method in the object.

If you don’t need to support old versions of Python, then using this solution may not cause any issues.

3. Make checking easy with isiterable()

If you have many variables and objects with unknown data types, it will be inconvenient to check the objects one by one.

I recommend you create a custom function that returns True when an object is iterable or False otherwise.

You can name the function as isiterable():

def isiterable(obj):
    try:
        iterable = iter(obj)
        return True
    except:
        return False

Anytime you want to check if an object is iterable, you just call the function as follows:

# Test 1
score = 90

if isiterable(score):
    print("Object is iterable")
else:
    print("Object is not iterable")  # ✅


# Test 2
my_list = [1, 2, 3]

if isiterable(my_list):
    print("Object is iterable")  # ✅
else:
    print("Object is not iterable")  

The isiterable() function will make checking for iterable objects convenient and easy. 😉

Conclusion

This article has shown different ways to check if an object is iterable in Python.

You can use the iter() function and a try-except block, or isinstance() and an if-else block.

Knowing how to check if an object is iterable can be useful to avoid TypeError when you do a for loop or a list comprehension with the object.

I hope this article was helpful. See you again in other articles! 👋