Set
Mutable, unordered, unique objects. Elements must be hashable.
Advantages: Searching is O(1). Lots of useful methods.
Disadvantages: Not ordered. Elements must be hashable.
Creating
# create a empty set
s = set()
# create a set with elements
s = {1,2,3} # Python 2.7, 3.x
Creating from another type
s = set([1,2,3]) # From list
s = set((1,2,3)) # From tuple
s = set('abc') # From string
Adding a value
s = {1,2,3}
s.add(4)
s # {1,2,3,4}
s.add(4)
s # {1,2,3,4} — duplicates are ignored
Adding multiple values
s = {1,2,3}
s.update([3,4,5]) # Any iterable will do
s # {1,2,3,4,5} — duplicates ignored
Removing an element
s = {1,2,3}
s.remove(1)
s # {2,3}
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