# Set (Class)

In: | set.rb
Parent: | Object

Set implements a collection of unordered values with no duplicates. This is a hybrid of Array’s intuitive inter-operation facilities and Hash’s fast lookup.

Several methods accept any Enumerable object (implementing `each`) for greater flexibility: new, replace, merge, subtract, |, &, -, ^.

The equality of each couple of elements is determined according to Object#eql? and Object#hash, since Set uses Hash as storage.

Finally, if you are using class Set, you can also use Enumerable#to_set for convenience.

## Example

      require 'set'
      s1 = Set.new [1, 2]                   # -> #<Set: {1, 2}>
      s2 = [1, 2].to_set                    # -> #<Set: {1, 2}>
      s1 == s2                              # -> true
      s1.add("foo")                         # -> #<Set: {1, 2, "foo"}>
      s1.merge([2, 6])                      # -> #<Set: {6, 1, 2, "foo"}>
      s1.subset? s2                         # -> false
      s2.subset? s1                         # -> true

## Methods

& + - << == [] ^ add add? classify clear collect! delete delete? delete_if difference divide dup each empty? flatten flatten! include? inspect intersection length map! member? merge new proper_subset? proper_superset? reject! replace size subset? subtract superset? to_a union |

## Included Modules

Enumerable

## Public Class methods

[](*ary)

Creates a new set containing the given objects.

[Source]

    # File set.rb, line 55
      def self.[](*ary)
        new(ary)
      end

new(enum = nil) {|o| ...}

Creates a new set containing the elements of the given enumerable object.

If a block is given, the elements of enum are preprocessed by the given block.

[Source]

    # File set.rb, line 64
      def initialize(enum = nil, &block) # :yields: o

        @hash ||= Hash.new

        enum.nil? and return

        if block
          enum.each { |o| add(block[o]) }
        else
          merge(enum)
        end
      end

## Public Instance methods

dup()

Duplicates the set.

[Source]

    # File set.rb, line 77
      def dup
        myhash = @hash
        self.class.new.instance_eval {
          @hash.replace(myhash)
          self
        }
      end

size()

Returns the number of elements.

[Source]

    # File set.rb, line 86
      def size
        @hash.size
      end

length()

Alias for size

empty?()

Returns true if the set contains no elements.

[Source]

    # File set.rb, line 92
      def empty?
        @hash.empty?
      end

clear()

Removes all elements and returns self.

[Source]

    # File set.rb, line 97
      def clear
        @hash.clear
        self
      end

replace(enum)

Replaces the contents of the set with the contents of the given enumerable object and returns self.

[Source]

    # File set.rb, line 104
      def replace(enum)
        if enum.class == self.class
          @hash.replace(enum.instance_eval { @hash })
        else
          enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
          clear
          enum.each { |o| add(o) }
        end

        self
      end

to_a()

Converts the set to an array. The order of elements is uncertain.

[Source]

    # File set.rb, line 117
      def to_a
        @hash.keys
      end

flatten()

Returns a new set that is a copy of the set, flattening each containing set recursively.

[Source]

    # File set.rb, line 142
      def flatten
        self.class.new.flatten_merge(self)
      end

flatten!()

Equivalent to Set#flatten, but replaces the receiver with the result in place. Returns nil if no modifications were made.

[Source]

    # File set.rb, line 148
      def flatten!
        if detect { |e| e.is_a?(Set) }
          replace(flatten())
        else
          nil
        end
      end

include?(o)

Returns true if the set contains the given object.

[Source]

    # File set.rb, line 157
      def include?(o)
        @hash.include?(o)
      end

member?(o)

Alias for include?

superset?(set)

Returns true if the set is a superset of the given set.

[Source]

    # File set.rb, line 163
      def superset?(set)
        set.is_a?(Set) or raise ArgumentError, "value must be a set"
        return false if size < set.size
        set.all? { |o| include?(o) }
      end

proper_superset?(set)

Returns true if the set is a proper superset of the given set.

[Source]

    # File set.rb, line 170
      def proper_superset?(set)
        set.is_a?(Set) or raise ArgumentError, "value must be a set"
        return false if size <= set.size
        set.all? { |o| include?(o) }
      end

subset?(set)

Returns true if the set is a subset of the given set.

[Source]

    # File set.rb, line 177
      def subset?(set)
        set.is_a?(Set) or raise ArgumentError, "value must be a set"
        return false if set.size < size
        all? { |o| set.include?(o) }
      end

proper_subset?(set)

Returns true if the set is a proper subset of the given set.

[Source]

    # File set.rb, line 184
      def proper_subset?(set)
        set.is_a?(Set) or raise ArgumentError, "value must be a set"
        return false if set.size <= size
        all? { |o| set.include?(o) }
      end

each() {|o| ...}

Calls the given block once for each element in the set, passing the element as parameter.

[Source]

    # File set.rb, line 192
      def each
        @hash.each_key { |o| yield(o) }
        self
      end

add(o)

Adds the given object to the set and returns self. Use `merge` to add several elements at once.

[Source]

    # File set.rb, line 199
      def add(o)
        @hash[o] = true
        self
      end

<<(o)

Alias for add

add?(o)

Adds the given object to the set and returns self. If the object is already in the set, returns nil.

[Source]

    # File set.rb, line 207
      def add?(o)
        if include?(o)
          nil
        else
          add(o)
        end
      end

delete(o)

Deletes the given object from the set and returns self. Use `subtract` to delete several items at once.

[Source]

    # File set.rb, line 217
      def delete(o)
        @hash.delete(o)
        self
      end

delete?(o)

Deletes the given object from the set and returns self. If the object is not in the set, returns nil.

[Source]

    # File set.rb, line 224
      def delete?(o)
        if include?(o)
          delete(o)
        else
          nil
        end
      end

delete_if() {|o| ...}

Deletes every element of the set for which block evaluates to true, and returns self.

[Source]

    # File set.rb, line 234
      def delete_if
        @hash.delete_if { |o,| yield(o) }
        self
      end

collect!() {|o| ...}

Do collect() destructively.

[Source]

    # File set.rb, line 240
      def collect!
        set = self.class.new
        each { |o| set << yield(o) }
        replace(set)
      end

map!()

Alias for collect!

reject!() {|o| ...}

Equivalent to Set#delete_if, but returns nil if no changes were made.

[Source]

    # File set.rb, line 249
      def reject!
        n = size
        delete_if { |o| yield(o) }
        size == n ? nil : self
      end

merge(enum)

Merges the elements of the given enumerable object to the set and returns self.

[Source]

    # File set.rb, line 257
      def merge(enum)
        if enum.class == self.class
          @hash.update(enum.instance_eval { @hash })
        else
          enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
          enum.each { |o| add(o) }
        end

        self
      end

subtract(enum)

Deletes every element that appears in the given enumerable object and returns self.

[Source]

    # File set.rb, line 270
      def subtract(enum)
        enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
        enum.each { |o| delete(o) }
        self
      end

|(enum)

Returns a new set built by merging the set and the elements of the given enumerable object.

[Source]

    # File set.rb, line 278
      def |(enum)
        enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
        dup.merge(enum)
      end

+(enum)

Alias for #|

union(enum)

Alias for #|

-(enum)

Returns a new set built by duplicating the set, removing every element that appears in the given enumerable object.

[Source]

    # File set.rb, line 287
      def -(enum)
        enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
        dup.subtract(enum)
      end

difference(enum)

Alias for #-

&(enum)

Returns a new array containing elements common to the set and the given enumerable object.

[Source]

    # File set.rb, line 295
      def &(enum)
        enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
        n = self.class.new
        enum.each { |o| include?(o) and n.add(o) }
        n
      end

intersection(enum)

Alias for #&

^(enum)

Returns a new array containing elements exclusive between the set and the given enumerable object. (set ^ enum) is equivalent to ((set | enum) - (set & enum)).

[Source]

    # File set.rb, line 306
      def ^(enum)
        enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
        n = dup
        enum.each { |o| if n.include?(o) then n.delete(o) else n.add(o) end }
        n
      end

==(set)

Returns true if two sets are equal. The equality of each couple of elements is defined according to Object#eql?.

[Source]

    # File set.rb, line 315
      def ==(set)
        equal?(set) and return true

        set.is_a?(Set) && size == set.size or return false

        set.all? { |o| include?(o) }
      end

classify() {|o| ...}

Classifies the set by the return value of the given block and returns a hash of {value => set of elements} pairs. The block is called once for each element of the set, passing the element as parameter.

e.g.:

      require 'set'
      files = Set.new(Dir.glob("*.rb"))
      hash = files.classify { |f| File.mtime(f).year }
      p hash    # => {2000=>#<Set: {"a.rb", "b.rb"}>,
                #     2001=>#<Set: {"c.rb", "d.rb", "e.rb"}>,
                #     2002=>#<Set: {"f.rb"}>}

[Source]

    # File set.rb, line 344
      def classify # :yields: o

        h = {}

        each { |i|
          x = yield(i)
          (h[x] ||= self.class.new).add(i)
        }

        h
      end

divide(&func)

Divides the set into a set of subsets according to the commonality defined by the given block.

If the arity of the block is 2, elements o1 and o2 are in common if block.call(o1, o2) is true. Otherwise, elements o1 and o2 are in common if block.call(o1) == block.call(o2).

e.g.:

      require 'set'
      numbers = Set[1, 3, 4, 6, 9, 10, 11]
      set = numbers.divide { |i,j| (i - j).abs == 1 }
      p set     # => #<Set: {#<Set: {1}>,
                #            #<Set: {11, 9, 10}>,
                #            #<Set: {3, 4}>,
                #            #<Set: {6}>}>

[Source]

    # File set.rb, line 371
      def divide(&func)
        if func.arity == 2
          require 'tsort'

          class << dig = {}         # :nodoc:

            include TSort

            alias tsort_each_node each_key
            def tsort_each_child(node, &block)
              fetch(node).each(&block)
            end
          end

          each { |u|
            dig[u] = a = []
            each{ |v| func.call(u, v) and a << v }
          }

          set = Set.new()
          dig.each_strongly_connected_component { |css|
            set.add(self.class.new(css))
          }
          set
        else
          Set.new(classify(&func).values)
        end
      end

inspect()

Returns a string containing a human-readable representation of the set. ("#<Set: {element1, element2, …}>")

[Source]

    # File set.rb, line 403
      def inspect
        ids = (Thread.current[InspectKey] ||= [])

        if ids.include?(object_id)
          return sprintf('#<%s: {...}>', self.class.name)
        end

        begin
          ids << object_id
          return sprintf('#<%s: {%s}>', self.class, to_a.inspect[1..-2])
        ensure
          ids.pop
        end
      end

[Validate]