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This module will teach you how to create empty tuples and tuples containing only one item.

Table of contents

Preface

This module is one in a collection of modules on Python designed for teaching ITSE 1359 Introduction to Scripting Languages: Python at Austin Community College in Austin, TX.

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find and view theFigures and the Listings while you are reading about them.

(Note to blind and visually impaired students: Most of the Figures and all of the Listings in this module are presented in plain text format and should be accessible using anaudio screen reader or a braille display.)

Figures

  • Figure 1 . Output from the code in Listing 1.
  • Figure 2 . Output from the code in Listing 2.
  • Figure 3 . Output from the code in Listing 3.
  • Figure 4 . Consolidated output from the program in Listing 4.
  • Figure 5 . Visualization of the tuples.

Listings

Introduction

This module is part of a series of modules designed to teach you about tuples in Python.

Previous modules have illustrated

  • How to create a tuple.
  • How to access a tuple item using indexing.
  • How to slice a tuple.
  • How to nest tuples.

This module will teach you how to create empty tuples and tuples containing only one item.

What is a tuple ?

A tuple is like a list whose values cannot be modified. It is an ordered list of objects, and it can contain references to any type of object.

  • Tuples are normally written as a sequence of items contained in (optional) matching parentheses.
  • A tuple is an immutable sequence.
  • Items in a tuple are accessed using a numeric index.
  • Tuples can be nested.

Sample Program

Empty, single-item, and nested tuples

Listing 4 shows a Python program that

  • Creates an empty tuple.
  • Creates a single-item tuple.
  • Nests the two tuples along with some strings in a third tuple.
  • Determines the length of each of the tuples.
  • Displays all of the above

A consolidated output from the program is shown in Figure 4 .

A visualization of the tuples in the program is provided in Figure 5 .

An empty tuple

I will explain this program in fragments. The beginning of the program is shown in Listing 1 .

Listing 1 . Beginning of the program.
# Illustrates empty tuples and tuples with only one element #----------------------------------------------------------print("Create and print empty tuple") t1 = ()print(t1) print("Length of empty tuple is")print(len(t1))

As you might have guessed from the name, an empty tuple is just a pair of empty parentheses as shown by the second statement in Listing 1 . (The parentheses aren't optional for an empty tuple.)

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Source:  OpenStax, Itse 1359 introduction to scripting languages: python. OpenStax CNX. Jan 22, 2016 Download for free at https://legacy.cnx.org/content/col11713/1.32
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