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Python•Foundations

Python Sets

Concept visual

Python Sets

keys map to buckets01kiwi:12pear:43apple:7grape:9
myset = {"apple", "banana", "cherry"}

Set

Sets are used to store multiple items in a single variable.

Formula

Set is one of 4 built - in data types in Python used to store collections of data, the other 3 are

List, Tuple, and Dictionary, all with different qualities and usage. A set is a collection which is unordered, unchangeable*, and unindexed. * Note: Set items are unchangeable, but you can remove items and add new items. Sets are written with curly brackets.

Example

Create a Set:

thisset = {"apple", "banana", "cherry"}
print(thisset)

Note:

Sets are unordered, so you cannot be sure in which order the items will appear.

Set Items

Set items are unordered, unchangeable, and do not allow duplicate values.

Unordered

Unordered means that the items in a set do not have a defined order. Set items can appear in a different order every time you use them, and cannot be referred to by index or key.

Unchangeable

Set items are unchangeable, meaning that we cannot change the items after the set has been created. Once a set is created, you cannot change its items, but you can remove items and add new items.

Duplicates Not Allowed

Sets cannot have two items with the same value.

Example

Duplicate values will be ignored:

thisset = {"apple", "banana", "cherry", "apple"}
print(thisset)

Note:

The values

True and

are considered the same value in sets, and are treated as duplicates:

Example

True and

is considered the same value:

thisset = {"apple", "banana", "cherry", True, 1, 2}
print(thisset)

Note:

The values

False and

are considered the same value in sets, and are treated as duplicates:

Example

False and

is considered the same value:

thisset = {"apple", "banana", "cherry", False, True, 0}
print(thisset)

Get the Length of a Set

To determine how many items a set has, use the len() function.

Example

Get the number of items in a set:

thisset = {"apple", "banana", "cherry"}
print(len(thisset))

Formula

Set Items - Data Types

Set items can be of any data type:

Example

String, int and boolean data types:

set1 = {"apple", "banana", "cherry"}
set2 = {1, 5, 7, 9, 3}
set3 = {True, False, False}

A set can contain different data types:

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Python - Access Set Items