Sets Module

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 &am; 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]:
    ...     group.discard('Susan')                  # unconditionally remove element
    ...     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([])

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