This blog is part of our Ruby 2.4 series.

Ruby has Enumerable#min and Enumerable#max which can be used to find the minimum and the maximum value in an Array.

(1..10).to_a.max
#=> 10
(1..10).to_a.method(:max)
#=> #<Method: Array(Enumerable)#max>

Ruby 2.4 adds Array#min and Array#max which are much faster than Enumerable#max and Enuermable#min.

Following benchmark is based on https://blog.blockscore.com/new-features-in-ruby-2-4 .

Benchmark.ips do |bench|
  NUM1 = 1_000_000.times.map { rand }
  NUM2 = NUM1.dup

  ENUM_MAX = Enumerable.instance_method(:max).bind(NUM1)
  ARRAY_MAX = Array.instance_method(:max).bind(NUM2)

  bench.report('Enumerable#max') do
    ENUM_MAX.call
  end

  bench.report('Array#max') do
    ARRAY_MAX.call
  end

  bench.compare!
end

Warming up --------------------------------------
      Enumerable#max     1.000  i/100ms
           Array#max     2.000  i/100ms
Calculating -------------------------------------
      Enumerable#max     17.569  (± 5.7%) i/s -     88.000  in   5.026996s
           Array#max     26.703  (± 3.7%) i/s -    134.000  in   5.032562s

Comparison:
           Array#max:       26.7 i/s
      Enumerable#max:       17.6 i/s - 1.52x  slower

Benchmark.ips do |bench|
  NUM1 = 1_000_000.times.map { rand }
  NUM2 = NUM1.dup

  ENUM_MIN = Enumerable.instance_method(:min).bind(NUM1)
  ARRAY_MIN = Array.instance_method(:min).bind(NUM2)

  bench.report('Enumerable#min') do
    ENUM_MIN.call
  end

  bench.report('Array#min') do
    ARRAY_MIN.call
  end

  bench.compare!
end

Warming up --------------------------------------
      Enumerable#min     1.000  i/100ms
           Array#min     2.000  i/100ms
Calculating -------------------------------------
      Enumerable#min     18.621  (± 5.4%) i/s -     93.000  in   5.007244s
           Array#min     26.902  (± 3.7%) i/s -    136.000  in   5.064815s

Comparison:
           Array#min:       26.9 i/s
      Enumerable#min:       18.6 i/s - 1.44x  slower

This benchmark shows that the new methods Array#max and Array#min are about 1.5 times faster than Enumerable#max and Enumerable#min.

Similar to Enumerable#max and Enumerable#min, Array#max and Array#min also assumes that the objects use Comparable mixin to define spaceship <=> operator for comparing the elements.