BigBinary Blog

Ruby 2.4 implements Array#min and Array#max

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

1
2(1..10).to_a.max
3#=> 10
4(1..10).to_a.method(:max)
5#=> #<Method: Array(Enumerable)#max>
6

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 .

1Benchmark.ips do |bench|
2  NUM1 = 1_000_000.times.map { rand }
3  NUM2 = NUM1.dup
4
5  ENUM_MAX = Enumerable.instance_method(:max).bind(NUM1)
6  ARRAY_MAX = Array.instance_method(:max).bind(NUM2)
7
8  bench.report('Enumerable#max') do
9    ENUM_MAX.call
10  end
11
12  bench.report('Array#max') do
13    ARRAY_MAX.call
14  end
15
16  bench.compare!
17end
18
19Warming up --------------------------------------
20      Enumerable#max     1.000  i/100ms
21           Array#max     2.000  i/100ms
22Calculating -------------------------------------
23      Enumerable#max     17.569  (± 5.7%) i/s -     88.000  in   5.026996s
24           Array#max     26.703  (± 3.7%) i/s -    134.000  in   5.032562s
25
26Comparison:
27           Array#max:       26.7 i/s
28      Enumerable#max:       17.6 i/s - 1.52x  slower
29
30Benchmark.ips do |bench|
31  NUM1 = 1_000_000.times.map { rand }
32  NUM2 = NUM1.dup
33
34  ENUM_MIN = Enumerable.instance_method(:min).bind(NUM1)
35  ARRAY_MIN = Array.instance_method(:min).bind(NUM2)
36
37  bench.report('Enumerable#min') do
38    ENUM_MIN.call
39  end
40
41  bench.report('Array#min') do
42    ARRAY_MIN.call
43  end
44
45  bench.compare!
46end
47
48Warming up --------------------------------------
49      Enumerable#min     1.000  i/100ms
50           Array#min     2.000  i/100ms
51Calculating -------------------------------------
52      Enumerable#min     18.621  (± 5.4%) i/s -     93.000  in   5.007244s
53           Array#min     26.902  (± 3.7%) i/s -    136.000  in   5.064815s
54
55Comparison:
56           Array#min:       26.9 i/s
57      Enumerable#min:       18.6 i/s - 1.44x  slower
58

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.