Table of contents
- Preface
- Introduction
- What is a tuple?
- Sample program
- Complete program listing
- Visualization of the tuples in the program
- 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 the Figuresand Listings while you are reading about them.
(Note to blind and visually impaired students: most of the Figures and all of the Listings inthis module are presented in plain text format and should be accessible using an audio 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 . Output from the code in Listing 4.
- Figure 5 . Visualization of the tuples in the program.
- Figure 6 . Output from the modified program.
Listings
- Listing 1 . Beginning of the program.
- Listing 2 . Unpack the tuple and print individual elements.
- Listing 3 . Unpack the tuple into the mutable list.
- Listing 4 . Complete program listing.
Introduction
This module is part of a series of modules designed to teach you about tuples.
Earlier modules have illustrated
- How to create (pack) a tuple.
- How to access a tuple item using indexing.
- How to slice a tuple.
- How to nest tuples.
- How to create empty tuples.
- How to create single-item tuples.
This module will teach you about unpacking tuples.
What is a tuple ?
A tuple is an immutable ordered list of objects. It can contain references to any type of object. See earlier modules in this series for a more detaileddescription.
Sample program
Program to unpack a tuple
Listing 4 presents a Python program that:
- Creates (packs) two simple tuples.
- Creates (packs) a third tuple by concatenating the first two tuples.
- Displays the third tuple.
- Unpacks the third tuple, assigning each item of the tuple into a separate variable.
- Displays each of the variables.
- Creates and displays a mutable list object containing five strings.
- Unpacks the tuple created earlier assigning the four items from the tuple into the first four items in the list.
- Displays the list.
Figure 4 shows the output produced by the program in Listing 4 .
Figure 5 shows a visualization of the tuples in the program after the first five statements in the code block have been executed.This is a case where you need to step through the program and observe changes in the diagram on the right to appreciate the behavior of the program.
I will explain this program in fragments. Listing 1 shows the beginning of the program.
Listing 1 . Beginning of the program. |
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# Illustrates unpacking a tuple
#------------------------------# Create a pair of tuples
t1 = 1,2t2 = "A","B"
# Concatenate and print themt3 = t1 + t2
print(t3) |