Sets Module - Unordered collections of unique elements

The sets module provides classes for constructing and manipulating unordered collections of unique elements.

engineers = Set(['John', 'Jane', 'Jack', 'Janice'])
programmers = Set(['Jack', 'Sam', 'Susan', 'Janice'])
managers = Set(['Jane', 'Jack', 'Susan', 'Zack'])
employees = engineers | programmers | managers             # union
engineering_management = engineers & managers           # intersection
fulltime_management = managers - engineers - programmers   # difference
engineers.add('Marvin')                                    # add element
print engineers    # Set(['Jane', 'Marvin', 'Janice', 'John', 'Jack'])
employees.issuperset(engineers)             # superset test
# False
employees.union_update(engineers)           # update from another set
employees.issuperset(engineers)
# True
for group in [engineers, programmers, managers, employees]:
     # unconditionally remove element
     group.discard('Susan')
     print group

Set(['Jane', 'Marvin', 'Janice', 'John', 'Jack'])
Set(['Janice', 'Jack', 'Sam'])
Set(['Jane', 'Zack', 'Jack'])
Set(['Jack', 'Sam', 'Jane', 'Marvin', 'Janice', 'John', 'Zack'])

s.symmetric_difference(t) - s ^ t - new set with elements in either s or t but not both.

Set([1,2,3]).symmetric_difference(Set([3,4,5]))   # Set([1,2,4,5])

s.copy() - new set with a shallow copy of s.

s = Set([1,2,3])
s.copy()   # Set([1, 2, 3])

s.discard(x) removes x from set s if present

s = Set([1,2,3])
s.discard(2)   # Set([1,3])

s.pop() remove and return an arbitrary element from s; raises KeyError if empty

s = Set([1,2,3])
s.pop()   # 3
s         # Set([1,2])

s.clear() remove all elements from set s

s = Set([1,2,3])
s.clear()
s   # Set([])