Overview
Python sets are used to store multiple items in a single variable, and unlike a list, are unordered, unchangeable, and unindexed.
Creating a Set
Sets are written with curly brackets. Set items are unchangeable, but items can be removed and new items can be added.
- Sets are unordered, so you cannot be sure in which order the items will appear (cannot be referred to by index or key)
- Sets are unchangeable once created, but items can be removed and new items added
- Set items can be of any data type (string, int, boolean, etc.)
- Each item in a set can be of a different data type
- Duplicate items are NOT allowed; if there are duplicates they will be ignored
- The values True and 1 are considered the same value in sets, and are treated as duplicates
- The values False and 0 are considered the same value in sets, and are treated as duplicates
my_set = {"Ferrari", "Maserati", "Alfa Romeo"}Using the set() Constructor to Create a Set
my_set = set(("Ferrari", "Maserati", "Alfa Romeo"))Getting the Number of Items in a Set
To determine how many items are in a set, the len() function is used.
my_set = {"Ferrari", "Maserati", "Alfa Romeo"}
print(len(my_set))3Sets are Defined as Objects with the Data Type ‘set’
my_set = {"Ferrari", "Maserati", "Alfa Romeo"}
print(type(my_set)) #<class 'set'>Python Notes:
- The most recent major version of Python is Python 3; however, Python 2 is still in use and quite popular, although not being updated with anything other than security updates
- Python uses new lines to complete a command, as opposed to other programming languages which often use semicolons or parentheses
- Python relies on indentation, using whitespace to define scope, such as the scope of loops, functions, and classes; other programming languages often use curly-brackets for this purpose
- Python string methods return new values, and DO NOT change the original string
- Python tuples are unchangeable after created (their items CANNOT be changed or re-ordered at a later point)
- Python sets are unordered (may appear in random orders when called), unchangeable (the value of individual items cannot be changed after creation), and unindexed (items cannot be referred to by index or key)
We’d like to acknowledge that we learned a great deal of our coding from W3Schools and TutorialsPoint, borrowing heavily from their teaching process and excellent code examples. We highly recommend both sites to deepen your experience, and further your coding journey. We’re just hitting the basics here at 1SMARTchicken.