Python: Insert a new item before the second element in an existing array
Last update on January 02 2021 11:02:28 (UTC/GMT +8 hours)(Python Example for Citizen Data Scientist & Business Analyst)
Write a Python program to insert a new item before the second element in an existing array.
Sample Solution:
Python Code :
Sample Output:
Original array: array('i', [1, 3, 5, 7, 9]) Insert new value 4 before 3: New array: array('i', [1, 4, 3, 5, 7, 9])Python List insert()
The Python List insert() method 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 than 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.
Example1: Inserting an Element to the List
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# 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)
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Output:
[1, 2, 3, 4, 10, 5, 6, 7] ['z', 'a', 'b', 'c', 'd', 'e']Example 2: Error of insert() Method
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# Python3 program for error
# of insert() method
# attribute error
string = "1234567"
string.insert(10, 1)
print(string)
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Output:
Traceback (most recent call last): File "/home/2fe54bd8723cd0ae89a17325da8b2eb5.py", line 7, in string.insert(10, 1) AttributeError: 'str' object has no attribute 'insert'Example 3: Insertion in a List Before any Element
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# 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)
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Output:
[1, 2, 13, 3, 4, 5, 6]Example 4: Inserting a Tuple to the List
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list1 = [ 1, 2, 3, 4, 5, 6 ]
# tuple of numbers
num_tuple = (4, 5, 6)
# inserting a tuple to the list
list1.insert(2, num_tuple)
print(list1)
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Output:
[1, 2, (4, 5, 6), 3, 4, 5, 6]Attention geek! Strengthen your foundations with the Python Programming Foundation Course and learn the basics.
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Inserting an element in list at specific index using list.insert()
In python list provides a member function insert() i.e.
It accepts a position and an element and inserts the element at given position in the list.
Let’s see an example,
Suppose we have a list of strings i.e.
Now let insert ‘why’ at 3rd position in the list i.e.
# Add an element at 3rd position in the list list1.insert(3, 'why')
Index will start from 0 in list. So, element will be inserted at 3rd position i.e. after 0,1 & 2.
So, list contents will be now,
Add an item to a list in Python (append, extend, insert)
In Python, use list methods append(), extend(), and insert() to add items (elements) to a list or combine other lists. You can also use the + operator to combine lists, or use slices to insert items at specific positions.
- Add an item to the end: append()
- Combine lists: extend(), + operator
- Insert an item at specified index: insert()
- Add another list or tuple at specified index: slice
Python lists
last modified December 15, 2021
In this part of the Python programming tutorial, we cover Python lists in more detail.
Python's .append(): Add Items to Your Lists in Place
Table of Contents
Watch Now This tutorial has a related video course created by the Real Python team. Watch it together with the written tutorial to deepen your understanding: Building Lists With Python's .append()
Adding items to a list is a fairly common task in Python, so the language provides a bunch of methods and operators that can help you out with this operation. One of those methods is .append(). With .append(), you can add items to the end of an existing list object. You can also use .append() in a for loop to populate lists programmatically.
In this tutorial, you’ll learn how to:
- Work with .append()
- Populate lists using .append() and a for loop
- Replace .append() with list comprehensions
- Work with .append() in array.array() and collections.deque()
You’ll also code some examples of how to use .append() in practice. With this knowledge, you’ll be able to effectively use .append() in your programs.
Free Download: Get a sample chapter from Python Basics: A Practical Introduction to Python 3 to see how you can go from beginner to intermediate in Python with a complete curriculum, up-to-date for Python 3.8.
Python List insert()
In this tutorial, we will learn about the Python List insert() method with the help of examples.
The insert() method inserts an element to the list at the specified index.