How to Check If a Variable Is a Dictionary in Python?

Question

How would you check if a variable is a dictionary in Python?

For example, I'd like it to loop through the values in the dictionary until it finds a dictionary. Then, loop through the one it finds:

dict = {'abc': 'abc', 'def': {'ghi': 'ghi', 'jkl': 'jkl'}}
for k, v in dict.iteritems():
    if ###check if v is a dictionary:
        for k, v in v.iteritems():
            print(k, ' ', v)
    else:
        print(k, ' ', v)

Accepted Answer

You could use if type(ele) is dict or use isinstance(ele, dict) which would work if you had subclassed dict:

d = {'abc': 'abc', 'def': {'ghi': 'ghi', 'jkl': 'jkl'}}
for element in d.values():
    if isinstance(element, dict):
       for k, v in element.items():
           print(k,' ',v)

Answer 2

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How would you check if a variable is a dictionary in Python?

This is an excellent question, but it is unfortunate that the most upvoted answer leads with a poor recommendation, type(obj) is dict.

(Note that you should also not use dict as a variable name - it's the name of the builtin object.)

If you are writing code that will be imported and used by others, do not presume that they will use the dict builtin directly - making that presumption makes your code more inflexible and in this case, create easily hidden bugs that would not error the program out.

I strongly suggest, for the purposes of correctness, maintainability, and flexibility for future users, never having less flexible, unidiomatic expressions in your code when there are more flexible, idiomatic expressions.

is is a test for object identity. It does not support inheritance, it does not support any abstraction, and it does not support the interface.

So I will provide several options that do.

How to Check If a Variable Is a Dictionary in Python?

5 Answers

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How would you check if a variable is a dictionary in Python?

Robert Thorne