Page 383 - Computer Science V2.0 Class 11

13 LISTS AND TUPLES

Chapter Outline

13.1 List 13.2 Traversing a List
13.3 Nested Lists 13.4 Heterogeneous List
13.5 More Operations on Lists 13.6 List Methods
13.7 Tuples 13.8 Tuple Operations
13.9 Tuple Methods

Introduction

In the last chapter, we learnt about strings and their several applications. However, a string is an immutable object,
and we cannot modify the elements of a string. Also, the elements of a string are constrained to be characters. These
restrictions are too harsh to develop practical applications. For example, while dealing with the students' data, we may
like to store their roll numbers, names, addresses, academic records, etc. Also, the data relating to a student, such as
his/her address and academic record, may change over a period of time. To deal with such situations, in this chapter
we will discuss two types of objects, namely, lists and tuples. Elements of a list or tuple may be of arbitrary types.
Whereas lists are mutable, tuples are immutable. Like strings, objects in a list appear in sequence and can be accessed
using indexes.

13.1 List

A list comprises a comma-separated sequence of objects enclosed in square brackets []. Like strings, elements of a list
may be accessed using indexing. Let us begin by creating a list of colours.

>>> colors = ['red', 'green', 'blue', 'pink', 'orange', 'white', 'black']
>>> colors
['red', 'green', 'blue', 'pink', 'orange', 'white', 'black']

Non-negative 0 1 2 3 4 5 6
indices
'red' 'green' 'blue' 'pink' 'orange' 'white' 'black'

Negative -7 -6 -5 -4 -3 -2 -1
indices

Lists and Tuples 369