Basic Python Programming Code Snippets:

Set Data Structure

Create a Set

You can create a set in two ways. You can either:

• assign your variable to a specified group of elements enclosing them with curly braces.
• variable = {x, y, z}

or;


• assign your variable to a list data structure and use the set() constructor which takes the list as a parameter.
• variable = set([x, y, z])
• variable = set(myList) # myList is a list of U.S. States. See the article on List Data Structure

The example below uses the first option of manually specifying the elements of the set and enclosing them in curly braces.

mySet = { 'Florida',
'Illinois',
'Pennsylvania',
'Ohio',
'Georgia',
'North Carolina',
'Michigan',
'Virginia',
'Washington',
'Massachusetts',
'Arizona',
'Indiana',
'Tennessee',
'Missouri',
'Maryland',
'Wisconsin',
'Minnesota',
'Colorado',
 'Alabama',
 'South Carolina',
 'Louisiana',
'Kentucky',
'Oregon',
 'Oklahoma',
 'Connecticut',
 'Iowa',
 'Arkansas',
'Mississippi',
 'Utah',
 'Kansas',
'Nevada',
'New Mexico',
'Nebraska',
'West Virginia',
 'Idaho',
 'Hawaii',
 'Maine',
 'New Hampshire',
'Rhode Island',
 'Montana',
'Delaware',
 'South Dakota',
 'North Dakota',
'Alaska',
'Vermont',
'Wyoming',
'New Jersey',
'New York',
'California',
'Texas'}

Add/Remove Elements

Once a set is created, you can add or remove elements using the add() and remove() methods.

The following syntax is used to add an element to a set.

mySet.add('DummyState')

The following syntax is used to remove an element from a set.

mySet.remove('DummyState')

Accessing Elements of a Set

Unlike lists and tuples, you cannot use indexing to access an element in a set. For sets, accessing elements require a loop.

for x in mySet:
  print(x)

Union, Intersection, and Difference

You can perform set operations such as union, intersection, and difference on your newly created sets. Operators ( |, &, - ) are used to accomplish this task.

Start by Creating Two Sets

set1 = {'DummyState1','DummyState2','DummyState3','DummyState3'}
set2 = {'Hawaii','Alaska','DummyState1','Florida'}

Perform Union Operation

union = set1 | set2     # a print of the object union returns {'DummyState1','DummyState2','DummyState3','DummyState3','Hawaii','Alaska','DummyState1','Florida'}

Perform Intersection Operation

intersection = set1 & set2     # a print of the object intersection returns {'DummyState1'}

Perform Difference Operation

difference = set1 - set2     # a print of the object difference returns {'DummyState2','DummyState3','DummyState3'}