A set is a data structure that holds elements in no particular order. An efficient back-end data structure for sets is the hash map. In python, sets can be defined using curly braces
x = {2, 8, 3}
print(x)
Set containment works with the in command
print(8 in x)
print(10 in x)
We can add elements to sets with the add command
x.add(5)
print(x)
We can remove elements with the remove command
x.remove(3)
print(x)
If we add an element that's already there, it doesn't change the set
x.add(8)
print(x)
A map is just like a set, except there is an associated value with every element. The lookup element is referred to as the key. We can think of a map like a dictionary where the key is the word and the value is the definition. In fact, python calls their version of a map a "dictionary" for this very reason. Python dictionaries can also be defined with curly braces, except we specify both a key and a value with the key:value syntax
people = {"chris":31, "celia":31, "theo":8, "layla":9}
We can check to see if a key is there, just as we did with a set
print("chris" in people)
print("nick" in people)
We can also add elements, though the syntax is slightly different and looks more like array syntax; the key is in brackets, and the value is on the right hand side of an assignment
people["nick"] = 100
print(people)