Solve - TypeError: 'type' object is not iterable in Python


Borislav Hadzhiev

Last updated: Apr 20, 2022


Check out my new book

Solve - TypeError: 'type' object is not iterable in Python #

The Python "TypeError: 'type' object is not iterable" occurs when we try to iterate over a class that is not iterable, e.g. forget to call the range() function. To solve the error, make the class iterable by implementing the __iter__() method.

typeerror type object is not iterable

Here is an example of how the error occurs when the range function.
# ⛔️ TypeError: 'type' object is not iterable for i in range: print(i)

If you use the range function, make sure to call it.
for i in range(0, 3): # 👉️ 0, 1, 2 print(i)

The range class is commonly used for looping a specific number of times in for loops and takes the following parameters:

startAn integer representing the start of the range (defaults to 0)
stopGo up to, but not including the provided integer
stepRange will consist of every N numbers from start to stop (defaults to 1)

If you only pass a single argument to the range() constructor, it is considered to be the value for the stop parameter.

If values for the start and stop parameters are provided, the start value is inclusive, whereas the stop value is exclusive.

You will also get the error if you try to iterate over a class that doesn't implement the __iter__() method.
class Counter: pass # ⛔️ TypeError: 'type' object is not iterable for c in Counter: print(c)

If you need to make the class iterable, implement the __iter__ method.
class Counter: def __init__(self, start, stop): self.current = start - 1 self.stop = stop def __iter__(self): return self def __next__(self): self.current += 1 if self.current < self.stop: return self.current raise StopIteration for c in Counter(0, 4): print(c) # 👉️ 0, 1, 2, 3

The __iter__() method is implicitly called at the start of loops and returns the iterator object.

The __next__() method is implicitly called at each loop increment and returns the next value.

If you need to check if an object is iterable, use a try/except statement.
my_str = 'hello' try: my_iterator = iter(my_str) for i in my_iterator: print(i) # 👉️ h, e, l, l, o except TypeError as te: print(te)

The iter() function raises a TypeError if the passed in value doesn't support the __iter__() method or the sequence protocol (the __getitem__() method).

If we pass a non-iterable object like a class to the iter() function, the except block is ran.

Examples of iterables include all sequence types (list, str, tuple) and some non-sequence types like dict, file objects and other objects that define an __iter__() or a __getitem__() method.

I wrote a book in which I share everything I know about how to become a better, more efficient programmer.
book cover
You can use the search field on my Home Page to filter through all of my articles.