Python list | insert()

insert() is an inbuilt function in Python that inserts a given element at a given index in a list.

Syntax :

list_name.insert(index, element)

Parameters :

index - the index at which the element has to be inserted.
element - the element to be inserted in the list.

Returns :

This method does not return any value but
it inserts the given element at the given index.

Error :

If anything other then a list is used with 
insert(), then it returns an AttributeError.

Note : If given index >= length(list) is given, then it inserts at the end of the list.

Code #1 :

# Python3 program for use  
# of insert() method 

list1 = [ 1, 2, 3, 4, 5, 6, 7 ] 

# insert 10 at 4th index 
list1.insert(4, 10) 
print(list1) 

list2 = ['a', 'b', 'c', 'd', 'e'] 

# insert z at the front of the list
list2.insert(0, 'z')
print(list2) 

Output :

[1, 2, 3, 4, 10, 5, 6, 7]
['z', 'a', 'b', 'c', 'd', 'e']

 
Code #2 :

# Python3 program for error  
# of insert() method 

# attribute error 
string = "1234567"

string.insert(10, 1)
print(string) 

Output :

Traceback (most recent call last):
  File "/home/2fe54bd8723cd0ae89a17325da8b2eb5.py", line 7, in 
    string.insert(10, 1)
AttributeError: 'str' object has no attribute 'insert'

 

Practical Application :
Insertion in a list before any element :

Code #3 :

# Python3 program for Insertion in a list  
# before any element using insert() method 

list1 = [ 1, 2, 3, 4, 5, 6 ]

# Element to be inserted 
element = 13 

# Element to be inserted before 3
beforeElement = 3 

# Find index
index = list1.index(beforeElement) 

# Insert element at beforeElement 
list1.insert(index, element) 
print(list1)

Output :

[1, 2, 13, 3, 4, 5, 6]

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