Module: Enumerable

Defined in:
activesupport/lib/active_support/json/encoding.rb,
activesupport/lib/active_support/core_ext/enumerable.rb

Instance Method Summary (collapse)

Instance Method Details

- (Object) as_json(options = nil)

:nodoc:



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# File 'activesupport/lib/active_support/json/encoding.rb', line 209

def as_json(options = nil) #:nodoc:
  to_a.as_json(options)
end

- (Object) each_with_object(memo, &block)



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# File 'activesupport/lib/active_support/core_ext/enumerable.rb', line 78

def each_with_object(memo, &block)
  each do |element|
    block.call(element, memo)
  end
  memo
end

- (Boolean) exclude?(object)

The negative of the Enumerable#include?. Returns true if the collection does not include the object.



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# File 'activesupport/lib/active_support/core_ext/enumerable.rb', line 104

def exclude?(object)
  !include?(object)
end

- (Object) group_by



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# File 'activesupport/lib/active_support/core_ext/enumerable.rb', line 22

def group_by
  assoc = ActiveSupport::OrderedHash.new

  each do |element|
    key = yield(element)

    if assoc.has_key?(key)
      assoc[key] << element
    else
      assoc[key] = [element]
    end
  end

  assoc
end

- (Object) index_by

Convert an enumerable to a hash. Examples:

people.index_by(&:login)
  => { "nextangle" => <Person ...>, "chade-" => <Person ...>, ...}
people.index_by { |person| "#{person.first_name} #{person.last_name}" }
  => { "Chade- Fowlersburg-e" => <Person ...>, "David Heinemeier Hansson" => <Person ...>, ...}


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# File 'activesupport/lib/active_support/core_ext/enumerable.rb', line 92

def index_by
  Hash[map { |elem| [yield(elem), elem] }]
end

- (Boolean) many?(&block)

Returns true if the collection has more than 1 element. Functionally equivalent to collection.size > 1. Can be called with a block too, much like any?, so people.many? { |p| p.age > 26 } returns true if more than 1 person is over 26.



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# File 'activesupport/lib/active_support/core_ext/enumerable.rb', line 98

def many?(&block)
  size = block_given? ? count(&block) : self.size
  size > 1
end

- (Object) sum(identity = 0, &block)

Calculates a sum from the elements. Examples:

payments.sum { |p| p.price * p.tax_rate }
payments.sum(&:price)

The latter is a shortcut for:

payments.inject(0) { |sum, p| sum + p.price }

It can also calculate the sum without the use of a block.

[5, 15, 10].sum # => 30
["foo", "bar"].sum # => "foobar"
[[1, 2], [3, 1, 5]].sum => [1, 2, 3, 1, 5]

The default sum of an empty list is zero. You can override this default:

[].sum(Payment.new(0)) { |i| i.amount } # => Payment.new(0)


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# File 'activesupport/lib/active_support/core_ext/enumerable.rb', line 57

def sum(identity = 0, &block)
  if block_given?
    map(&block).sum(identity)
  else
    inject { |sum, element| sum + element } || identity
  end
end