Python

insert() method in list

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insert() method in list - Python

It is used to insert an element to a list at the specified position.

This method directly modifies the original list and it doesn’t return anything.

It takes exactly two arguments first is index position and the second one is element that you want to insert.

When we call .insert() method with an index position and an element then first it will check the index position whether it is in valid range(smaller than length of list) or not if it is in range then it right shifts all element to free up space of given index position and then insert the element at given index position if index is not in valid range and index is positive then it will insert element at last and if given index value is negative then it will insert element at beginning of the list.

You can also pass negative index to the insert method.

The .insert() method takes O(n) time complexity where n is the number of elements.

Syntax –

list.insert(index,element)

Parameter –

index → index position where you want to insert element.

element → element that you want to insert in the list e.g. int, float, tuple etc.

return → None( it doesn’t return anything).

Example – insert 1 at index 0 in a list

				
					my_list=[2,3,4,5,6]
print("Original list:",my_list)
my_list.insert(0,1)
print("Original list after inserting 1 at index 0")
print(my_list)

# Output -
# Original list: [2, 3, 4, 5, 6]
# Original list after inserting 1 at index 0
# [1, 2, 3, 4, 5, 6]

In the above example, first we create a list with element from 2 to 6 and store it in the my_list variable.

After creating original list print the original list on the output screen.

Then insert 1 at index 0 using the .insert() method.

Finally, print the modified original list on the output screen.

Example 2- insert a list to the list at specified position

				
					my_list=['Hello', 'everyone', 'this','is']
my_list1=['edSlash', 'official']
print("Original list:",my_list)
my_list.insert(4,my_list1)
print("Original list after inserting another list:")
print(my_list)

# Output -
# Original list: ['Hello', 'everyone', 'this', 'is']
# Original list after inserting another list: 
# ['Hello', 'everyone', 'this', 'is', ['edSlash', 'official']]

Example 3- insert element outside of the list range

				
					lst=[10,20,30,40,50]
print("Original list:",lst)
lst.insert(6,60)        # will insert 60 at the end 
print("Modified list:",lst)
# Output -
# Original list: [10, 20, 30, 40, 50]
# Modified list: [10, 20, 30, 40, 50, 60]

Example 4- insert a string to the list at specified position

				
					my_list=['a','b','d','e','f']
print("Original list", my_list)
my_list.insert(2,'c')
print("Modified original list:",my_list)

# Output -
# Original list ['a', 'b', 'd', 'e', 'f']
# Modified original list: ['a', 'b', 'c', 'd', 'e', 'f']

Difference between insert and append method of list in Python?

insert()	append()
It is used to insert an element to a list at specified position.	It adds an element to the end of the list
It takes two arguments the index position where element has to be inserted and the element itself.	It takes only element as an argument.
The time complexity of insert method is O(n)	The time complexity of append method is O(1).

Python

insert() method in list

insert() method in list - Python

Difference between insert and append method of list in Python?

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