Python List

Python list is ordered data type i.e. with heterogeneous data. List are enclosed in brackets [] with items comma separated. The list is the most widely used data type in Python.

How to create a list in Python?

List in Python is created using big brackets [] with the items in the list be separated by a comma (,).  A list can have any number of items and can be of different data types. To have an idea of python data types, please refer to this tutorial:- Python Datatypes.

Let’s explore some of the examples of the list in the following example:-

emptyList = []
colors = ['red', 'green', 'blue']
numbers = [1, 2, 3, 4, 5, 6]
mixed = ['John', 103, 10.2]
matrix = [[1, 2, 3], [4, 5, 6]]

print(emptyList)
print(colors)
print(numbers)
print(mixed)
print(matrix)

The output of the above program is:-

How to access elements in a list in Python?

We can use a slice operator [] and [:] to get items in the list. The concatenation operation can be done using plus (+) sign and asterisk(*) serves as the repetition operator. We can use two types of indexing to get items viz. positive indexing and negative indexing. Positive indexing allows to index items from 0 to n where negative index gives access from backward, where -1 is the last item.

Below is an example of list with simple operations:-

list = ['abcd', 786 , 2.23, 'john', 70.2]
print(list)          # Prints complete list
print(list[0])       # Prints first element of the list
print(list[1:3])     # Prints elements starting from 2nd till 3rd
print(list[2:])      # Prints elements starting from 3rd element
print(list[-1])      # Prints last element

Output:-

How to change or add elements to a list in Python?

Since lists are mutable data types, you can add, edit or delete every item in a list. It is the most flexible data type in Python. You can use a particular index or slice operator to select more than one items to update the value of the list in that position.

colors = ['red', 'green', 'blue']
print("Current list", colors)
colors[1] = 'black'
print("Updated new color", colors)

To add elements in the list, append() method of the list is used.

colors = ['red', 'green', 'blue']
print("Current list", colors)
colors.append('gray')
print("Updated new color", colors)

 How to delete or remove elements from a list in Python?

We can use del function to remove the whole list or index of items in the list.

colors = ['red', 'green', 'blue', 'gray', 'black']
print("Current list", colors)
del(colors[1])  #removes the color green
print("Updated list", colors)
del(colors[1:3])
print("Updated list", colors)

How to iterate over a List in Python?

A list can be iterated using for loop. Let us see the following example:-

colors = ['red', 'green', 'blue', 'gray', 'black']
for color in colors:
    print(color)

What are Python List Operations?

What are Python List Built-in functions?

Python provides the following built-in functions which can be used with the lists.

What are Python List built-in methods?

Python provides various methods that can help you perform the various operations in a list. Following are some of the built-in list methods:-