How to check if an object is iterable in Python

Three methods to check iteration status of a variable in python.

An iterable is an object which can be traversed. Data structures like array, string, and tuples are iterables.

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In certain cases, e.g., when dealing with custom data types, we may not know whether an object is iterable, but for this there should be some kind of mechanism through which a user can estimate its iterable status.

In this article, we will see how we can identify if an object is iterable using three techniques.

1. Iterating over the object¶

This is the simplest way to check if an object is iterable.

try:
  _ = [element for element in target_variable]
except TypeError:
  print("Object not an iterable")
else:
  print("Object is iterable")

This style of programming is called duck typing ("If it looks like a duck and quacks like a duck, it must be a duck.").

2. Using iter()¶

If an object is iterable, it will not throw an error when used with iter(). It checks if the passed object has __iter__() or __getitem__() method available, which are methods that iterables possess.

try:
  iter(target_variable)
except TypeError:
  print("Object not an iterable")
else:
  print("Object is iterable")

3. Using collection.abc.Iterable¶

The collection library houses specialized container datatypes and abstract base classes to test if a class provides particular interfaces. Coupled with built-in isinstance() method we can get a boolean response. This technique does not work with classes that implement __getitem__() dunder method.

from collection.abc import Iterable

if isintance(target_variable, Iterable):
  print("Object is iterable")
else:
  print("Object not an iterable")