The last container object we introduce in this section is defined by the data type set.
Sets are containers that share properties and operations with sets in mathematics. A mathematical set is a collection of distinct objects. Like in mathematics, in Python the elements of a set are also listed within a pair of braces.
Here are some mathematical set expressions:
And here are their Python counterparts:
A = {1,2,3,4} B = {5} C = A.union(B) # returns{1,2,3,4,5} D = A.intersection(C) # returns {1,2,3,4} E = C.difference(A) # returns {5} 5 in C # returns True
Sets contain an element only once, corresponding to the aforementioned definition:
A = {1,2,3,3,3} B = {1,2,3} A == B # returns True
Moreover, a set is unordered; that is, the order of the elements in the set is not defined:
A = {1,2,3} B = {1,3,2} A == B # returns True
Sets in Python can contain all kinds of immutable objects, that is, numeric objects, strings...