filter_map VS map + compact

select_and_map_VS_map_and_compact_VS_filter_map.rb

require 'benchmark/ips'

Benchmark.ips do |bm|
  # Create a list with 10_000 elements and some nil values
  list = (0..10_000).to_a

  fn = ->(x) { x+1 if x.even? }

  bm.report "select + map" do
    list.select {|x| x.even? }.map {|x| x+1 }
  end

  bm.report "map + compact" do
    list.map(&fn).compact
  end

  bm.report "filter_map" do
    list.filter_map(&fn)
  end

  bm.compare!
end

ruby 3.3.1 (2024-04-23 revision c56cd86388) [arm64-darwin23]
Warming up --------------------------------------
        select + map   216.000 i/100ms
       map + compact   227.000 i/100ms
          filter_map   206.000 i/100ms
Calculating -------------------------------------
        select + map      2.281k (± 3.7%) i/s  (438.45 μs/i) -     11.448k in   5.027572s
       map + compact      2.234k (± 6.6%) i/s  (447.65 μs/i) -     11.123k in   5.005639s
          filter_map      2.035k (± 1.5%) i/s  (491.41 μs/i) -     10.300k in   5.062578s

Comparison:
        select + map:     2280.8 i/s
       map + compact:     2233.9 i/s - same-ish: difference falls within error
          filter_map:     2035.0 i/s - 1.12x  slower