Multiset implements a collection of unordered
values and allows duplicates.
Example
require 'multiset'
s1 = Multiset.new [1, 2] # -> #<Multiset: {1, 2}>
s1.add(2) # -> #<Multiset: {1, 2, 2}>
s1.merge([2, 6]) # -> #<Multiset: {1, 2, 2, 2, 3}>
s1.multiplicity(2) # -> 3
s1.multiplicity(3) # -> 1
&(enum)
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Returns a new set containing elements common to the set and the given
enumerable object.
129: def &(enum)
130: s = dup
131: n = self.class.new
132: enum.each { |o|
133: if s.include?(o)
134: s.delete(o, 1)
135: n.add(o)
136: end
137: }
138: n
139: end
<<(o)
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==(set)
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^(enum)
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Returns a new set containing elements exclusive between the set and the
given enumerable object. (set ^ enum) is equivalent to ((set | enum) -
(set & enum)).
145: def ^(enum)
146: n = self.class.new(enum)
147: each { |o| n.include?(o) ? n.delete(o, 1) : n.add(o) }
148: n
149: end
add(o)
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Adds the given object to the set and returns self. Use merge to
add many elements at once.
80: def add(o)
81: @hash[o] ||= 0
82: @hash[o] += 1
83: self
84: end
cardinality()
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Returns the total number of elements in a multiset, including repeated
memberships
27: def cardinality
28: @hash.inject(0) { |s, (e, m)| s += m }
29: end
delete(o, n = nil)
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Deletes all the identical object from the set and returns self. If
n is given, it will remove that amount of identical objects from
the set. Use subtract to delete many different items at once.
93: def delete(o, n = nil)
94: if n
95: @hash[o] ||= 0
96: @hash[o] -= n if @hash[o] > 0
97: @hash.delete(o) if @hash[o] == 0
98: else
99: @hash.delete(o)
100: end
101: self
102: end
delete_if()
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Deletes every element of the set for which block evaluates to true, and
returns self.
108: def delete_if
109: each { |o| delete(o) if yield(o) }
110: self
111: end
each()
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Calls the given block once for each element in the set, passing the element
as parameter. Returns an enumerator if no block is given.
69: def each
70: @hash.each_pair do |key, multiplicity|
71: multiplicity.times do
72: yield(key)
73: end
74: end
75: self
76: end
eql?(set)
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Returns true if two sets are equal. Two multisets are equal if they have
the same cardinalities and each element has the same multiplicity in both
sets. The equality of each element inside the multiset is defined according
to Object#eql?.
155: def eql?(set)
156: return true if equal?(set)
157: set = self.class.new(set) unless set.is_a?(self.class)
158: return false unless cardinality == set.cardinality
159: superset?(set) && subset?(set)
160: end
length()
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merge(enum)
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Merges the elements of the given enumerable object to the set and returns
self.
115: def merge(enum)
116: enum.each { |o| add(o) }
117: self
118: end
multiplicity(e)
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Returns the number of times an element belongs to the multiset.
21: def multiplicity(e)
22: @hash[e]
23: end
proper_subset?(set)
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Returns true if the set is a proper subset of the given set.
60: def proper_subset?(set)
61: set.is_a?(self.class) or raise ArgumentError, "value must be a set"
62: return false if set.cardinality <= cardinality
63: all? { |o| multiplicity(o) <= set.multiplicity(o) }
64: end
proper_superset?(set)
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Returns true if the set is a proper superset of the given set.
46: def proper_superset?(set)
47: set.is_a?(self.class) or raise ArgumentError, "value must be a set"
48: return false if cardinality <= set.cardinality
49: set.all? { |o| set.multiplicity(o) <= multiplicity(o) }
50: end
size()
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subset?(set)
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Returns true if the set is a subset of the given set.
53: def subset?(set)
54: set.is_a?(self.class) or raise ArgumentError, "value must be a set"
55: return false if set.cardinality < cardinality
56: all? { |o| multiplicity(o) <= set.multiplicity(o) }
57: end
subtract(enum)
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Deletes every element that appears in the given enumerable object and
returns self.
122: def subtract(enum)
123: enum.each { |o| delete(o, 1) }
124: self
125: end
superset?(set)
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Returns true if the set is a superset of the given set.
39: def superset?(set)
40: set.is_a?(self.class) or raise ArgumentError, "value must be a set"
41: return false if cardinality < set.cardinality
42: set.all? { |o| set.multiplicity(o) <= multiplicity(o) }
43: end
to_a()
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Converts the set to an array. The order of elements is uncertain.
34: def to_a
35: inject([]) { |ary, (key, _)| ary << key }
36: end
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