Methods

Instance Public methods

exclude?(object)

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

📝 Source code 
# File activesupport/lib/active_support/core_ext/enumerable.rb, line 92
  def exclude?(object)
    !include?(object)
  end
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index_by()

Convert an enumerable to a hash.

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 ...>, ...}
📝 Source code 
# File activesupport/lib/active_support/core_ext/enumerable.rb, line 64
  def index_by
    if block_given?
      result = {}
      each { |elem| result[yield(elem)] = elem }
      result
    else
      to_enum(:index_by) { size if respond_to?(:size) }
    end
  end
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many?()

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

📝 Source code 
# File activesupport/lib/active_support/core_ext/enumerable.rb, line 78
  def many?
    cnt = 0
    if block_given?
      any? do |element|
        cnt += 1 if yield element
        cnt > 1
      end
    else
      any? { (cnt += 1) > 1 }
    end
  end
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pluck(*keys)

Convert an enumerable to an array based on the given key.

[{ name: "David" }, { name: "Rafael" }, { name: "Aaron" }].pluck(:name)
# => ["David", "Rafael", "Aaron"]

[{ id: 1, name: "David" }, { id: 2, name: "Rafael" }].pluck(:id, :name)
# => [[1, "David"], [2, "Rafael"]]
📝 Source code 
# File activesupport/lib/active_support/core_ext/enumerable.rb, line 114
  def pluck(*keys)
    if keys.many?
      map { |element| keys.map { |key| element[key] } }
    else
      map { |element| element[keys.first] }
    end
  end
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sum(identity = nil, &block)

Calculates a sum from the elements.

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)
📝 Source code 
# File activesupport/lib/active_support/core_ext/enumerable.rb, line 38
    def sum(identity = nil, &block)
      if identity
        _original_sum_with_required_identity(identity, &block)
      elsif block_given?
        map(&block).sum(identity)
      else
        inject(:+) || 0
      end
    end
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without(*elements)

Returns a copy of the enumerable without the specified elements.

["David", "Rafael", "Aaron", "Todd"].without "Aaron", "Todd"
# => ["David", "Rafael"]

{foo: 1, bar: 2, baz: 3}.without :bar
# => {foo: 1, baz: 3}
📝 Source code 
# File activesupport/lib/active_support/core_ext/enumerable.rb, line 103
  def without(*elements)
    reject { |element| elements.include?(element) }
  end
🔎 See on GitHub