How to append None to a list?

The None keyword in Python represents the absence of a value or a null value, so it is mostly used to initialize a variable or to signify the end of a function or it acts as a placeholder for future data.

Let's see how we can append None to a list in Python.

Using append() method

The append() method is the most simple and straightforward way to add None at the end of a list.

a = [2, 3] 
# Append None to the list
a.append(None)

print(None)

None

Explanation: append() adds a single element to the end of the list, here None is appended as an individual element.

Let's explore some other ways to append None to a Python list'

Using insert() method

If we want to add None at a specific position in the list than we can use the insert() method.

a = [1, 2, 3]
#Inserting None at the second position(index 1)
a.insert(1, None)

print(a)

[1, None, 2, 3]

EXPLANATION: Here insert(index, value) adds the particular value at the specified index, which is None in this case.

Using Slicing

We can use slicing to add None at the end of the list.

a = [1, 2, 3]
#Appending None using slicing
a[len(a) :] = [None]

print(a)

Explanation: Here a[len(a):] is used to target the position at the end of the list and [None] creates a new list containing None, which is then added to the original list by using slicing.

Using List Concatenation

Another way to append None is by concatenating a list with [None] to the existing list.

a = [1, 2, 3]
#Appending None using list concatenation
a = a + [None]

print(a)

[1, 2, 3, None]

Explanation: The '+' operator concatenates the [None] list to the original list.

Using a Function Call

We can create a function to append None to a list and call it whenever need.

#define a function to append None
def append_none(a):
  a.append(None)
#Create a list  
b = [1, 2, 3]
#Call the function
append_none(b)

print(b)

[1, 2, 3, None]