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How to Solve Python TypeError: ‘builtin_function_or_method’ object is not iterable

by | Programming, Python, Tips

This error occurs when you try to iterate over a builtin_function_or_method object, for example, using a for loop.

If your built-in function or method returns an iterable object, you can solve the error by adding parentheses () after the method name to call it and return the object. For example,

particle_dict = {"name":"muon", "charge":-1, "mass":105.7}

for val in particle_dict.values():

    print(val)

This tutorial will detail the error and how to solve it with code examples.

Table of contents

TypeError: ‘builtin_function_or_method’ object is not iterable

TypeError occurs in Python when you perform an illegal operation for a specific data type. A builtin_function_or_method is a method or a function that is built into the Python interpreter, and we cannot iterate over it.

What is an Iterable Object in Python?

An iterable is an object that can be “iterated over“, for example in a for loop. In terms of dunder methods under the hood, an object can be iterated over with “for” if it implements __iter__() or __getitem__().

An iterator returns the next value in the iterable object. An iterable generates an iterator when it is passed to the iter() method.

In terms of dunder methods under the hood, an iterator is an object that implements the __next__() method.

A for loop automatically calls the iter() method to get an iterator and then calls next over and over until it reaches the end of the iterable object.

Example #1

Let’s look at an example of trying to iterate over a built-in method.

First, we will define a string then attempt to split the string using the method split() and then iterate over the substrings.

string = "Python.is.really.fun.to.learn"

for word in string.split:

    print(ch)

Let’s run the code to see what happens:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Input In [10], in <cell line: 3>()
      1 string = "Python.is.really.fun.to.learn"
----> 3 for word in string.split:
      5     print(ch)

TypeError: 'builtin_function_or_method' object is not iterable

The error occurs because we did not call the split() method. Therefore Python interprets the for loop as trying to iterate over the split method object, which is not iterable.

Solution

We can solve this error by calling the method split() with the separator “.“. We can call a method by specifying the method name and putting parentheses after the name. Let’s look at the revised code.

string = "Python.is.really.fun.to.learn"

for word in string.split("."):

    print(ch)

Let’s run the code to get the substrings:

Python
is
really
fun
to
learn

Example #2

Let’s look at a second example of trying to iterate over a built-in function or method.

First, we will define a dictionary containing information about the muon particle:

particle_dict = {"name":"muon", "charge":-1, "mass":105.7}

Then we will try to iterate over the values in the dictionary using the dict method values().

for val in particle_dict.values:
    print(val)

Let’s run the code to see what happens:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Input In [15], in <cell line: 1>()
----> 1 for val in particle_dict.values:
      2     print(val)

TypeError: 'builtin_function_or_method' object is not iterable

The error occurs because we did not call the values method. Therefore Python interprets the for loop as trying to iterate over the values method object, which is not iterable.

Solution

We can solve this error by calling the method values(). We can call a method by specifying the method name and putting parentheses after the name. Let’s look at the revised code:

particle_dict = {"name":"muon", "charge":-1, "mass":105.7}
for val in particle_dict.values():
    print(val)

Let’s run the code to get the values in the dictionary:

muon
-1
105.7

Summary

Congratulations on reading to the end of this tutorial!

For more reading on not iterable TypeErrors, go to the article:

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