Set

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

Public Class Methods

[](*ary) click to toggle source

Creates a new set containing the given objects.

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

new(enum = nil) click to toggle source

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.

 
               # 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

&(enum) click to toggle source

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

 
               # File set.rb, line 291
def &(enum)
  enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
  n = self.class.new
  enum.each { |o| n.add(o) if include?(o) }
  n
end

Also aliased as: intersection

+(enum) click to toggle source

Alias for: |

-(enum) click to toggle source

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

 
               # File set.rb, line 283
def -(enum)
  enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
  dup.subtract(enum)
end

Also aliased as: difference

<<(o) click to toggle source

Alias for: add

==(set) click to toggle source

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

 
               # File set.rb, line 311
def ==(set)
  equal?(set) and return true

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

  hash = @hash.dup
  set.all? { |o| hash.include?(o) }
end

^(enum) click to toggle source

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

 
               # File set.rb, line 302
def ^(enum)
  enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
  n = Set.new(enum)
  each { |o| if n.include?(o) then n.delete(o) else n.add(o) end }
  n
end

add(o) click to toggle source

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

 
               # File set.rb, line 195
def add(o)
  @hash[o] = true
  self
end

Also aliased as: <<

add?(o) click to toggle source

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

 
               # File set.rb, line 203
def add?(o)
  if include?(o)
    nil
  else
    add(o)
  end
end

classify() click to toggle source

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"}>}

 
               # File set.rb, line 342
def classify # :yields: o
  h = {}

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

  h
end

clear() click to toggle source

Removes all elements and returns self.

 
               # File set.rb, line 93
def clear
  @hash.clear
  self
end

collect!() click to toggle source

Do collect() destructively.

 
               # File set.rb, line 236
def collect!
  set = self.class.new
  each { |o| set << yield(o) }
  replace(set)
end

Also aliased as: map!

delete(o) click to toggle source

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

 
               # File set.rb, line 213
def delete(o)
  @hash.delete(o)
  self
end

delete?(o) click to toggle source

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

 
               # File set.rb, line 220
def delete?(o)
  if include?(o)
    delete(o)
  else
    nil
  end
end

delete_if() click to toggle source

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

 
               # File set.rb, line 230
def delete_if
  to_a.each { |o| @hash.delete(o) if yield(o) }
  self
end

difference(enum) click to toggle source

Alias for: -

divide(&func) click to toggle source

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}>}>

 
               # File set.rb, line 369
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

each() click to toggle source

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

 
               # File set.rb, line 188
def each
  @hash.each_key { |o| yield(o) }
  self
end

empty?() click to toggle source

Returns true if the set contains no elements.

 
               # File set.rb, line 88
def empty?
  @hash.empty?
end

flatten() click to toggle source

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

 
               # File set.rb, line 138
def flatten
  self.class.new.flatten_merge(self)
end

flatten!() click to toggle source

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

 
               # File set.rb, line 144
def flatten!
  if detect { |e| e.is_a?(Set) }
    replace(flatten())
  else
    nil
  end
end

include?(o) click to toggle source

Returns true if the set contains the given object.

 
               # File set.rb, line 153
def include?(o)
  @hash.include?(o)
end

Also aliased as: member?

initialize_copy(orig) click to toggle source

Copy internal hash.

 
               # File set.rb, line 77
def initialize_copy(orig)
  @hash = orig.instance_eval{@hash}.dup
end

inspect() click to toggle source

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

 
               # File set.rb, line 401
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

intersection(enum) click to toggle source

Alias for: &

length() click to toggle source

Alias for: size

map!() click to toggle source

Alias for: collect!

member?(o) click to toggle source

Alias for: include?

merge(enum) click to toggle source

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

 
               # File set.rb, line 253
def merge(enum)
  if enum.is_a?(Set)
    @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

proper_subset?(set) click to toggle source

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

 
               # File set.rb, line 180
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

proper_superset?(set) click to toggle source

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

 
               # File set.rb, line 166
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

reject!() click to toggle source

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

 
               # File set.rb, line 245
def reject!
  n = size
  delete_if { |o| yield(o) }
  size == n ? nil : self
end

replace(enum) click to toggle source

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

 
               # File set.rb, line 100
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

size() click to toggle source

Returns the number of elements.

 
               # File set.rb, line 82
def size
  @hash.size
end

Also aliased as: length

subset?(set) click to toggle source

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

 
               # File set.rb, line 173
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

subtract(enum) click to toggle source

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

 
               # File set.rb, line 266
def subtract(enum)
  enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
  enum.each { |o| delete(o) }
  self
end

superset?(set) click to toggle source

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

 
               # File set.rb, line 159
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

to_a() click to toggle source

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

 
               # File set.rb, line 113
def to_a
  @hash.keys
end

union(enum) click to toggle source

Alias for: |

|(enum) click to toggle source

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

 
               # File set.rb, line 274
def |(enum)
  enum.is_a?(Enumerable) or raise ArgumentError, "value must be enumerable"
  dup.merge(enum)
end

Also aliased as: +, union

Protected Instance Methods

flatten_merge(set, seen = Set.new) click to toggle source

 
               # File set.rb, line 117
def flatten_merge(set, seen = Set.new)
  set.each { |e|
    if e.is_a?(Set)
      if seen.include?(e_id = e.object_id)
        raise ArgumentError, "tried to flatten recursive Set"
      end

      seen.add(e_id)
      flatten_merge(e, seen)
      seen.delete(e_id)
    else
      add(e)
    end
  }

  self
end

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