struct

Multiset(T)

Inherits Iterable < Enumerable < Struct < Value < Object

A Multiset (or bag) is a collection of unordered elements that is similar to a set, but allows duplicate values.

Multiset uses Hash as storage.

ms1 = Multiset.new [1, 2]
ms2 = Multiset{2, 1}
ms1 == ms2          # => true
ms1.add(2)          # => Multiset{1, 2, 2}
ms1.merge([2, 6])   # => Multiset{1, 2, 2, 2, 6}
ms1.multiplicity(2) # => 3
ms1.subset_of? ms2  # => false
ms2.subset_of? ms1  # => true

Constants

VERSION = {{ (`shards version /tmp/tmp.oaFMOa/src/src`).chomp.stringify }}

Constructors

new(enumerable : Enumerable(T))

Creates a new multiset from the elements in enumerable.

Multiset.new([1, 2, 3, 1]) # => Multiset{1, 1, 2, 3}

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new(initial_capacity = nil)

Create a new empty Multiset.

If an initial_capacity is given, it will set the initial capacity of the internal Hash.

ms = Multiset(Int32).new
ms.empty # => true

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Instance methods

&(other : Multiset)

Returns a new multiset by performing multiset intersection with other.

For each element, new multiplicity is minimum multiplicity in either multiset

ms1 = Multiset{1, 1, 1, 2, 2, 3, 4, 5}
ms2 = Multiset{1, 1, 3, 3, 6}
ms3 = Multiset{'a', 1, 1}

ms1 & ms2 # => Multiset{1, 1, 3}
ms1 & ms3 # => Multiset{1, 1}

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&(other : Enumerable)

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*(sf : Int32)

Scales the multiplicity of all elements by sf and returns self.

Multiset{1, 2, 2} * 2 # => Multiset{1, 1, 2, 2, 2, 2}

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+(other)

Returns a new multiset containing the elements from both self and other.

Multiset{1, 2, 3} + Multiset{3, 4, 5} # => Multiset{1, 2, 3, 3, 4, 5}
Multiset{1, 2, 3} + [3, 4, 5]         # => Multiset{1, 2, 3, 3, 4, 5}

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-(other : Enumerable)

Returns a new multiset with all elements in other removed.

Multiset{1, 2, 3} - [1, 3] # => Multiset{2}

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<<(object : T)

Alias for add.

ms = Multiset{1, 2, 3}
ms << 4 # => Multiset{1, 2, 3, 4}

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==(other : Multiset)

Returns true if both multisets contain the same elements.

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==(other : Set)

Returns true if both sets contain the same elements.

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^(other : Enumerable)

Returns a new multiset by performing symmetric difference with other.

For each element, new multiplicity is absolute difference between multiplicity in either multiset.

ms1 = Multiset{1, 1, 1, 2, 2, 3, 4, 5}
ms2 = Multiset{1, 1, 3, 3, 6}
ms3 = Multiset{'a', 1, 1}

ms1 ^ ms2 # => Multiset{1, 2, 2, 3, 4, 5, 6}
ms1 ^ ms3 # => Multiset{'a', 1, 2, 2, 3, 4, 5}

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|(other : Enumerable)

Returns a new multiset by performing mutiset union with other.

For each element, new multiplicity is maximum multiplicity in either multiset.

ms1 = Multiset{1, 1, 1, 2, 2, 3, 4, 5}
ms2 = Multiset{1, 1, 3, 3, 6}
ms3 = Multiset{'a', 1, 1}

ms1 | ms2 # => Multiset{1, 1, 1, 3, 3, 6, 2, 2, 4, 5}
ms1 | ms3 # => Multiset{'a', 1, 1, 1, 2, 2, 3, 4, 5}

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add(object : T, count : Int32)

Increments multiplicity of object by count and returns self.

ms = Multiset{1, 2, 3}
ms.add(4, 2) # => Multiset{1, 2, 3, 4, 4}

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add(object : T)

Increments multiplicity of object and returns self.

ms = Multiset{1, 2, 3}
ms.add(4) # => Multiset{1, 2, 3, 4}

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clear

Removes all elements and returns self.

ms = Multiset{1, 2, 2}
ms.clear
ms.empty? # => true

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compare_by_identity

Makes this multiset compare objects using their object_id.

ms = Multiset{"string"}
ms.includes?("str" + "ing") # => true

ms.compare_by_identity
ms.includes?("str" + "ing") # => false

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compare_by_identity?

Returns true if the multiset is comparing objects by object_id.

See compare_by_identity.

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delete(object, count : Int32)

Decrements multiplicity of object by count and returns self.

Multiset{1, 2, 3}.delete(2, 1) # => Multiset{1, 3}
Multiset{4, 4, 5}.delete(4, 2) # => Multiset{5}

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delete(object)

Decrements multiplicity of object and returns self.

Multiset{1, 2, 3}.delete(2) # => Multiset{1, 3}
Multiset{4, 4, 5}.delete(4) # => Multiset{4, 5}

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dup

Returns a new Multiset with the same elements.

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each

Yields each element of the multiset, and returns self.

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each

Returns an iterator for each element of the multiset.

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empty?

Returns true if the multiset has no elements.

Multiset(Int32).new.empty? # => true
Multiset{1, 2, 3}.empty?   # => false

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hash(hasher)

See Object#hash(hasher)

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includes?(object)

Returns true if object is an element in the multiset.

Multiset{1, 2, 3}.includes?(3)   # => true
Multiset{1, 2, 3}.includes?(4)   # => false
Multiset{1, 2, 3}.includes?('a') # => false

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inspect(io : IO) : Nil

Alias of #to_s.

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intersects?(other : Multiset)

Returns true if the multiset has any element in common with other.

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merge(other : Multiset(T))

Adds each element of other and returns self.

ms = Multiset{3, 4, 5}
Multiset{1, 2, 3}.merge(ms) # => Multiset{1, 2, 3, 3, 4, 5}

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merge(elems)

Adds each element of elems and returns self.

ms = Multiset{1, 2, 3}
ms.merge([3, 4, 5]) # => Multiset{1, 2, 3, 3, 4, 5}

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multiplicity(object : T)

Returns count of object in the multiset.

ms = Multiset{1, 2, 2}
ms.multiplicity(1) # => 1
ms.multiplicity(2) # => 2

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multiplicity(object : U) forall U

Returns 0.

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proper_subset?(other : Multiset)

Returns true if the multiset is a proper subset of other.

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proper_subset_of?(other : Multiset) : Bool

Returns true if the multiset is a proper subset of other.

Mutiset{1, 2}.proper_subset_of? Multiset{1, 2, 3} # => true
Mutiset{1, 2}.proper_subset_of? Multiset{1, 1, 2} # => true
Mutiset{1, 2}.proper_subset_of? Multiset{1, 2}    # => false

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proper_superset?(other : Multiset)

Returns true if the multiset is a proper superset of other.

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proper_superset_of?(other : Multiset) : Bool

Returns true if the multiset is a proper superset of other.

Mutiset{1, 2, 3}.proper_superset_of? Multiset{1, 2} # => true
Mutiset{1, 1, 2}.proper_superset_of? Multiset{1, 2} # => true
Mutiset{1, 2}.proper_superset_of? Multiset{1, 2}    # => false

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size

Returns the number of elements in the multiset.

Multiset{1, 2, 3}.size       # => 3
Multiset{1, 1, 1, 2, 3}.size # => 5

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subset?(other : Multiset)

Returns true if the multiset is a subset of other.

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subset_of?(other : Multiset) : Bool

Returns true if the multiset is a subset of other.

Mutiset{1, 2}.subset_of? Multiset{1, 2, 3} # => true
Mutiset{1, 2}.subset_of? Multiset{1, 1, 2} # => true
Mutiset{1, 2}.subset_of? Multiset{1, 2}    # => true

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subtract(other : Multiset)

Removes all elements in other and returns self.

ms = Multiset{1, 2, 3}
ms.subtract(Multiset{1, 3}) # => Multiset{2}

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subtract(other : Enumerable)

Removes all elements in other and returns self.

ms = Multiset{1, 2, 3}
ms.subtract([1, 3]) # => Multiset{2}

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superset?(other : Multiset)

Returns true if the multiset is a superset of other.

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superset_of?(other : Multiset) : Bool

Returns true if the multiset is a superset of other.

Mutiset{1, 2, 3}.superset_of? Multiset{1, 2} # => true
Mutiset{1, 1, 2}.superset_of? Multiset{1, 2} # => true
Mutiset{1, 2}.superset_of? Multiset{1, 2}    # => true

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to_s(io : IO) : Nil

Writes a string representation of the multiset to io.

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uniq

Returns an Array containing unique elements from the multiset.

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