method

divide

v1_8_7_72 - Show latest stable - 0 notes - Class: Set

divide(&func) public

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}>}>

Show source

# File lib/set.rb, line 375
  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

divide

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