In this article, we are going to see how to iterate through a nested List. A list can be used to store multiple Data types such as Integers, Strings, Objects, and also another List within itself. This sub-list which is within the list is what is commonly known as the Nested List.
Iterating through a Nested List
Lets us see how a typical nested list looks like :
![list=[10, 20, 30, 40, [ 80,60, 70 ] ]](https://geeksforgeeks.org/wp-content/uploads/2023/10/quicklatex.com-262edd8187fe178ada23c5e6df0a2d7e_l3.png "Rendered by QuickLaTeX.com")
There are multiple ways to iterate through a Nested List:
Method 1: Use of the index to iterate through the list
Use of Positive Index:
Python3
# codelist = [10, 20, 30, 40, [80, 60, 70]] # Printing sublist at index 4print(list[4]) # Printing 1st element of the sublistprint(list[4][0]) # Printing 2nd element of the sublistprint(list[4][1]) # Printing 3rd element of the sublistprint(list[4][2]) |
Output:
[80, 60, 70] 80 60 70
Use of Negative Index
Python3
# codelist = [10, 20, 30, 40, [80, 60, 70]] # Printing sublist at index 4print(list[-1]) # Printing 1st element of the sublistprint(list[-1][-3]) # Printing 2nd element of the sublistprint(list[-1][-2]) # Printing 3rd element of the sublistprint(list[-1][-1]) |
Output:
[80, 60, 70] 80 60 70
Method 2: Use of loop to iterate through the list
Python3
# code# LISTlist = [["Rohan", 60], ["Aviral", 21], ["Harsh", 30], ["Rahul", 40], ["Raj", 20]] # looping through nested list using indexesfor names in list: print(names[0], "is", names[1], "years old.") |
Output:
Rohan is 60 years old. Aviral is 21 years old. Harsh is 30 years old. Rahul is 40 years old. Raj is 20 years old.
Use of Temporary Variables inside a loop.
Python3
# code# LISTlist = [["Rohan", 60], ["Aviral", 21], ["Harsh", 30], ["Rahul", 40], ["Raj", 20]] # looping through nested list using multiple # temporary variablesfor name, age in list: print(name, "is", age, "years old.") |
Output:
Rohan is 60 years old. Aviral is 21 years old. Harsh is 30 years old. Rahul is 40 years old. Raj is 20 years old.
Method 3: Use of Slicing
Python3
# code# listlist = [10, 20, 30, 40, [80, 60, 70]] # print the entire Sublist at index 4print(list[4][:]) # printing first two elementprint(list[4][0 : 2]) |
Output:
[80, 60, 70] [80, 60]
