Class: Array

Inherits:
Object
  • Object
show all
Includes:
Combinatorics::CartesianProduct::Mixin, Combinatorics::Choose::Mixin, Combinatorics::Derange::Mixin, Combinatorics::Permute::Mixin, Combinatorics::PowerSet::Mixin
Defined in:
lib/combinatorics/list_comprehension.rb,
lib/combinatorics/choose/extensions/array.rb,
lib/combinatorics/derange/extensions/array.rb,
lib/combinatorics/permute/extensions/array.rb,
lib/combinatorics/power_set/extensions/array.rb,
lib/combinatorics/cartesian_product/extensions/array.rb

Instance Method Summary collapse

Methods included from Combinatorics::CartesianProduct::Mixin

#cartesian_product

Methods included from Combinatorics::PowerSet::Mixin

#powerset

Methods included from Combinatorics::Permute::Mixin

#permute

Methods included from Combinatorics::Derange::Mixin

#derange

Methods included from Combinatorics::Choose::Mixin

#choose

Instance Method Details

#comprehension {|list| ... } ⇒ Enumerator

Iterates over each permutation of the enumerable values within the Array.

Examples:

[(1..5),(1..4),(1..3)].comprehension.to_a
# => [
  [1, 1, 1], [1, 1, 2], [1, 1, 3],
  [1, 2, 1], [1, 2, 2], [1, 2, 3],
  [1, 3, 1], [1, 3, 2], [1, 3, 3],
  [1, 4, 1], [1, 4, 2], [1, 4, 3],
  [2, 1, 1], [2, 1, 2], [2, 1, 3],
  [2, 2, 1], [2, 2, 2], [2, 2, 3],
  [2, 3, 1], [2, 3, 2], [2, 3, 3],
  [2, 4, 1], [2, 4, 2], [2, 4, 3],
  [3, 1, 1], [3, 1, 2], [3, 1, 3],
  [3, 2, 1], [3, 2, 2], [3, 2, 3],
  [3, 3, 1], [3, 3, 2], [3, 3, 3],
  [3, 4, 1], [3, 4, 2], [3, 4, 3],
  [4, 1, 1], [4, 1, 2], [4, 1, 3],
  [4, 2, 1], [4, 2, 2], [4, 2, 3],
  [4, 3, 1], [4, 3, 2], [4, 3, 3],
  [4, 4, 1], [4, 4, 2], [4, 4, 3],
  [5, 1, 1], [5, 1, 2], [5, 1, 3],
  [5, 2, 1], [5, 2, 2], [5, 2, 3],
  [5, 3, 1], [5, 3, 2], [5, 3, 3],
  [5, 4, 1], [5, 4, 2], [5, 4, 3]
]

Yields:

  • (list) —

    The given block will be passed each permutation of the enumerable values in the Array.

Yield Parameters:

  • list (Array) —

    A permutation of the enumerable values within the Array.

Returns:

  • (Enumerator) —

    If no block is given, an enumerator object will be returned.



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# File 'lib/combinatorics/list_comprehension.rb', line 46

def comprehension
  return enum_for(:comprehension) unless block_given?

  if empty?
    yield self
    return nil
  end

  enums = self.map do |value|
    case value
    when Combinatorics::Enumerator
      value
    when Enumerable
      value.enum_for
    else
      [value].enum_for
    end
  end

  iteration = enums.map { |e| e.next }

  loop do
    yield iteration.dup

    (enums.length - 1).downto(0) do |index|
      begin
        iteration[index] = enums[index].next
        break
      rescue StopIteration
        enums[index].rewind
        iteration[index] = enums[index].next
      end

      return nil if index == 0
    end
  end
end