Table of contents
- Preface
- Introduction
- What is a tuple?
- Sample program
- Complete program listing
- Visualization of the tuples
- Run the program
- Miscellaneous
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
- Listing 1 . Beginning of the program.
- Listing 2 . A tuple with only one element.
- Listing 3 . Create and print nested tuples.
- Listing 4 . Create and print nested tuples.
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. |
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# 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.)