Python if type is dictionary

How to Check if a Variable is a Dictionary in Python: 7 Methods to Use

Learn how to check if a variable is a dictionary in Python with 7 different methods, including isinstance(), iterating over dict items, using type() method in Jinja, and more.

• Using isinstance() method
• Iterating over dict items
• Using type() method in Jinja
• Using membership operator “in”
• Using locals() function
• The collections.Mapping ABC
• Other quick code examples for checking if a variable is a dictionary in Python
• Conclusion
• Is there == for dict in Python?
• How do you check if a value is a dictionary Python?
• How do you check if a variable is a key in a dictionary Python?
• How do you check if something is in a dict?

Python is a versatile programming language that is widely used for various applications such as data analysis, web development, artificial intelligence, and machine learning. One of the most common tasks in Python is checking if a variable is a dictionary. In this blog post, we will explore different ways to check if a variable is a dictionary in python.

Using isinstance() method

The isinstance() method is a built-in function in Python that checks if a variable is an instance of a specified class or its subclass. You can use isinstance(v, collections.abc.Mapping) to check if a variable is a dictionary. The collections.abc.Mapping class is an abstract base class that defines the behavior of a mapping, which includes a dictionary. You can also use isinstance(v, dict) to check if v is an instance of a dictionary.

import collectionsmy_dict = <> print(isinstance(my_dict, collections.abc.Mapping)) # True print(isinstance(my_dict, dict)) # True 

Iterating over dict items

Another way to check if a variable is a dictionary is to iterate over dict items and check their types to determine if they are key-value pairs. You can use list comprehension to iterate over a sequence of all the key-value pairs in the dictionary and create a bool list. The bool list can be checked to determine if the variable is a dictionary.

my_dict = <> print(isinstance(my_dict, dict)) # Truetry: iter(my_dict.items()) print(True) except AttributeError: print(False) 

Using type() method in Jinja

Jinja is a popular templating engine used in web development that allows for dynamic content rendering. You can use the type(x)==dict expression to check if a variable is a dictionary in Jinja.

Using membership operator “in”

You can check if a key exists or not in a dictionary using the membership operator “in”. The membership operator checks if a key exists in the dictionary and returns a boolean value. You can also use the get() method to check if a key exists in the Python dictionary. The get() method returns the value of the key if it exists in the dictionary, else it returns None.

my_dict = print("name" in my_dict) # True print("address" in my_dict) # False# Using get() method print(my_dict.get("name")) # John print(my_dict.get("address")) # None 

You can also use the keys() method to check if a key exists in the dictionary. The keys() method returns a list of all the keys in the dictionary.

my_dict = print("name" in my_dict.keys()) # True print("address" in my_dict.keys()) # False 

In versions older than Python 3, you can also use the has_key() method to check if a key exists in the dictionary.

my_dict = print(my_dict.has_key("name")) # True print(my_dict.has_key("address")) # False 

Using locals() function

You can use the locals() function to check the existence of variables locally in Python. The locals() function returns a dictionary containing the current scope’s local variables and their values.

my_dict = print("my_dict" in locals()) # True 

The collections.Mapping ABC

The collections.Mapping ABC provides a simple way to check if the object behaves like a dictionary. This abstract base class defines the behavior of a mapping type, which includes a dictionary.

import collectionsmy_dict = <> print(isinstance(my_dict, collections.Mapping)) # True 

Other quick code examples for checking if a variable is a dictionary in Python

In Python , for instance, python is dict code sample

squares = print(type(squares) is dict) # True print("memory address of type(squares):", id(type(squares))) print("memory address of dict:", id(dict)) # Should have same ID as type(squares)

In Python , for example, python if type dict code example

my_dict = isinstance(,dict) print("my_dict is a dict:", my_dict) 

Conclusion

In this blog post, we covered various ways to check if a variable is a dictionary in Python. These methods include using the isinstance() method, iterating over dict items, using the type() method in Jinja, using membership operator “in”, using the get() method, using the locals() function, and using the collections.Mapping ABC. By using these methods, developers can ensure that their code is efficient and error-free.

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Python: Check if Variable is a Dictionary

Variables act as a container to store data. A developer can use type hints when creating variables or passing arguments, however, that’s an optional feature in Python, and many codebases, old and new, are yet to have them. It’s more common for a variable in Python to have no information of the type being stored.

If we had code that needed a dictionary but lacked type hints, how can we avoid errors if the variable used is not a dictionary?

In this tutorial, we’ll take a look at how to check if a variable is a dictionary in Python, using the type() and isinstance() functions, as well as the is operator:

Developers usually use type() and is , though, these can be limited in certain contexts, in which case, it’s better to use the isinstance() function.

Check if Variable is a Dictionary with type()

We can use the type() function to instantly get the type of any variable. For a variable of type Dictionary , it must return :

squares = 1: 1, 2: 4, 3: 9> print(type(squares)) 

Check if Variable is a Dictionary with is Operator

In Python, is is an identity operator. It verifies if both the operands are identical to each other. Being identical indicates that they refer to the same memory location.

We can use the is operator with the result of a type() call with a variable and the dict class. It will output True only if the type() points to the same memory location as the dict class. Otherwise, it will output False .

As a sanity check, we can use the id() function to get the address of the object in memory and verify the comparison:

squares = 1: 1, 2: 4, 3: 9> print(type(squares) is dict) # True print("memory address of type(squares):", id(type(squares))) print("memory address of dict:", id(dict)) # Should have same ID as type(squares) 

This code will produce the following output on a Python interpreter:

True memory address of type(squares): 1609576584 memory address of dict: 1609576584 

Note: The memory address may vary for you, but the same ID should be present for both the type(squares) and dict .

One caveat of this method is that it fails to work if the variable is a type that’s a subclass of dict . For example, the previous code would not work if the squares variable was an Ordered Dictionary instead:

from collections import OrderedDict squares = OrderedDict([(1, 1), (2, 4), (3, 9)]) print(type(squares) is dict) # False print("memory address of type(squares):", id(type(squares))) print("memory address of dict:", id(dict)) # Different ID as they're different classes 

False memory address of type(squares): 9464512 memory address of dict: 9481952 

If your code is required to work on subclasses of Dictionaries, then you would prefer to use the isinstance() method.

Check if Variable is a Dictionary with isinstance()

As we have seen, the is operator will return True when the memory address of both the objects is the same. If we have a Dictionary of type inherited from class dict , it will return False . For example, a Dictionary of a subclass of dict like OrderedDict or defaultdict will not point to the same memory address as of dict .

Here we have the isinstance() function to the rescue. This function takes two arguments; an object and a class. If the object is an instance of the class or its subclasses, it will return True . If the object is not an instance of the given class, whether direct or indirect, it returns False .

Here is a code example to check if the variable is a Dictionary using the isinstance() function:

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from collections import OrderedDict # Variable of type dict squares = 1: 1, 2: 4, 3: 9> print(isinstance(squares, dict)) # True # Variable of type OrderedDict (Subclass of dict) cubes = OrderedDict(((1, 1), (2, 8))) print(isinstance(cubes, dict)) # True 

This code will produce the following output on a Python interpreter:

Conclusion

This tutorial showed ways in which we can check if a variable is a Dictionary. We have first seen the type() function which outputs for any Dictionary object. Then we have seen the use of the is operator to check if the type of variable points to dict in the memory location. This returns True or False accordingly.

Lastly, we have seen that is fails at identifying inherited Dictionary objects. When we want to capture inherited objects, we can use the isinstance() function. It returns True if the object is directly or indirectly an instance of the given class ( dict in this article), and False otherwise.

As both these methods return True or False , we can easily use them in conditional statements. Unless you explicitly want to reject subclasses of dict , the isinstance() function is the most reliable way to check if a variable is a Dictionary.

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