programming-for-dummies

330
Using Sets
2. Assign each variable with a different name like this:
Day(0) = “Monday”
Day(1) = “Tuesday”
Day(2) = “Wednesday”
Day(3) = “Thursday”
Day(4) = “Friday”
Day(5) = “Saturday”
Day(6) = “Sunday”
This would store all the days of the week inside a single array variable,
although it requires multiple lines to store data in each array element.
However, there’s a simpler way to lump related data together — use a data
structure called a set. Like an array, a set groups data in a single variable
name, but a set has several advantages:
✦ You don’t have to define a fixed size ahead of time.
✦ You don’t have to identify each chunk of data with an index number.
✦ Sets can store a mixed variety of data types, such as Integers and
Strings. (An array can only hold a single data type.)
Defining a set lists all the data you want to store, as shown in this Python
programming language example:
from sets import Set
days = Set([‘Monday’, ‘Tuesday’, ‘Wednesday’, ‘Thursday’,
‘Friday’, ‘Saturday’, ‘Sunday’])
Certain features aren’t always a built-in part of a programming language,
such as sets in Python. Rather than create a complicated language with lots
of built-in features that not everyone will ever use, many programming languages
add additional features through libraries, which are separate subprograms.
For example, the Pascal language includes sets as a built-in data
structure but the Python language does not. To use sets in Python, you must
include (or import) a separate library that lets you use sets in a program. To
use sets in Python, you must use the Python library called (surprise!) Set.
In this Python language example, the variable days contains the entire set or
group of the days defined by the Set command. To print the contents of this
set, you can use a print command followed by the name of the set like this:
print days
This command would print:
Set([‘Monday’, ‘Tuesday’, ‘Wednesday’, ‘Thursday’, ‘Friday’,
‘Saturday’, ‘Sunday’])