None Data Type in Python with Example

None Data Type in Python with Example

Hello Techies,

In this blog, we will check in detail about “None data type in Python with Example”. Most of us have some questions regarding no datatype like, how to convert none to string or integer?, What is a ‘NoneType’ object? How to “test” NoneType in python? etc…So in this blog, I am going to solve all the doubts regarding None data type in Python, So check this blog till the end.

In my previous blog, I included built-in datatypes in Python. Check it out too.

Below are the Points that we are covering in this blog.

  1. What is None Data Type in Python
  2. How to “test” NoneType in python?
  3. How to convert None to String or Integer
  4. TypeError: ‘NoneType’ object is not subscriptable in python
  5. TypeError: ‘NoneType’ object is not iterable

#1. What is None Data Type in Python

  • None keyword is an object and is a data type of none type class.
  • None datatype doesn’t contain any value.
  • None keyword is used to define a null variable or object.
  • None keyword is immutable.

Syntax for None:

None

#2. How to “test” NoneType in python?

The following are some of the different scenarios for How to test NoneType in Python.

  • Check the type of None object
  • How to check if a variable is None using is operator
  • How to check if a variable is None using == operator
  • How to compare None with None type
  • How to compare None with False type
  • How to compare None with the empty string

Check the type of None object

# Declaring a variable with None type

typeOfNone = None 
type(typeOfNone)

Output:

<class 'NoneType'>

How to check if a variable is None using is operator

is operator used to compare the objects, not only equality but also the same object with the same memory location.

test1 = None

if test1 is None: # Checking if the variable is None
  print("None")
else:
  print("Not None")

Output:

None

How to check if a variable is None using == operator

The (==) operator compares the values of 2 objects or equality of two items.

test1 = None

if test1 == None: # Checking if the variable is None
  print("None")
else:
  print("Not None")

Output:

None
Interview Question & Answer:

Q: Difference between is and == in python

Ans: The "==" operator compares the values or equalities of two objects, 
         while the Python "is" operator checks whether the two variables point to  
         the same object in memory.

How to compare None with None type

print (None == None)

Output:

True

How to compare None with False type

print(None == False)

Output:

False

How to compare None with the empty string

print ("" == None)

Output:

False

#3. How to convert None to String or Integer?

value = None
str_result = "test" if value is None else value
int_result = 1 if value is None else value

print(str_result)
print(int_result)

Output:

test
1

#4. TypeError: ‘NoneType’ object is not subscriptable in python

‘NoneType’ object is not subscriptable in python, all of us have had to deal with this at least once while working on Python code. So let me give you an example of when such type of error occurs, and also tell you how to fix this error.

Example:

list1=[1,2,4,6]
reverse_ord=list1.reverse()
reverse_ord[2]

Output of this error program is:

Traceback (most recent call last):                                                                                            
    File "<stdin>", line 1, in <module>                                                                                   TypeError: 'NoneType' object is not subscriptable
Note: An error (TypeError: 'NoneType' object is not subscriptable) occurs 
           when you try to access an item with a None  value using the index.

How to avoid this error?

list1=[1,2,4,6]
list1.reverse()
reverse_ord[2]

#5. TypeError: ‘NoneType’ object is not iterable

TypeError: ‘NoneType’ object is not iterable“, all of us have had to deal with this at least once while working on Python code. So let me give you an example of when such type of error occurs, and also tell you how to fix this error.

Example:

def myfunction(data):
    for each in data:
        print(each)

myfunction(None)

In the example above, if the data is None, we get the error on the second line where we are iterating over the data object. This error occurs when we try to iterate on a None object.

How to avoid this error?

There are many ways to avoid such errors. Let’s check one by one.

One way to avoid this error is to check if the object is None before iterating it over the object.

def myfunction(data):
    if data is None:
        print ("Unable to iterate None Data")
    else:
        for each in data:
            print(each)

myfunction(None)

Another way to handle this error is to write a loop in the try-except block.

def myfunction(data):
    try:
        for each in data:
            print(each)
    except Exception as e:
        print("Error!!!",e)

myfunction(None)

So, using the above solutions, you can solve the problem of “TypeError: ‘NoneType’ object is not iterable“.


FAQ on None data type in Python

  1. Is none a data type in Python?

    Yes, None keyword is an object and is a data type of none type class in Python. None datatype doesn’t contain any value. None keyword is used to define a null variable or object.

  2. How do you check if a variable is none in Python?

    The following are some of the different scenarios for How to check NoneType in Python:

    1)Check the type of None object
    x = None
    type(x)

    2)Checking if a variable is None using is operator
    x = None
    result = print(“None”) if x is None else print(“Not None”)

    3)Checking if a variable is None using == operator
    x = None
    result = print(“None”) if x == None else print(“Not None”)

  3. How is none used in Python?

    None keyword is an object and is a data type of none type class. None keyword is used to define a null variable or object.

  4. Is an empty list none?

    No, if we assign a empty list to any variable, it will only return a empty list.

I hope you understand the usage of ‘none data type in python‘. Still you have any queries please comment below.

Check out the official site for more information on ‘none data type in python’.

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