fastest_map_hash.rb

require 'benchmark/ips'

Cart = Struct.new(:items)

N = 10_000

query = -> { Array.new(N).map { |a| Cart.new(%w(foo bar baz)) } }

Benchmark.ips do |x|
  x.report('each') do
    carts = query.()
    results = []
    carts.each do |cart|
      cart.items.each do |item|
        results << {name: item}
      end
    end
  end

  x.report('flat_map') do
    carts = query.()
    carts.flat_map do |cart|
      cart.items.map! { |item| {name: item} }
    end
  end

  x.report('map_flatten') do
    carts = query.()
    carts.map! do |cart|
      cart.items.map! { |item| {name: item} }
    end.flatten!
  end

  x.report('reduce') do
    carts = query.()
    carts.reduce([]) do |ary, cart|
      cart.items.each { |item| ary << {name: item} }
      ary
    end
  end

  x.report('each_with_object') do
    carts = query.()
    carts.each_with_object([]) do |cart, ary|
      cart.items.each { |item| ary << {name: item} }
    end
  end
end

# -*- mode: ruby-compilation; default-directory: "~/src/sandbox/" -*-
# RubyComp started at Tue Nov 11 13:29:01
# 
# ruby /home/jmdeldin/src/sandbox/fastest_map_hash.rb
# Calculating -------------------------------------
#                 each         6 i/100ms
#             flat_map         6 i/100ms
#          map_flatten         6 i/100ms
#               reduce         6 i/100ms
#     each_with_object         6 i/100ms
# -------------------------------------------------
#                 each       70.6 (±9.9%) i/s -        354 in   5.060102s
#             flat_map       64.9 (±3.1%) i/s -        330 in   5.088580s
#          map_flatten       60.4 (±8.3%) i/s -        300 in   5.004533s
#               reduce       69.4 (±10.1%) i/s -        348 in   5.064078s
#     each_with_object       68.3 (±7.3%) i/s -        342 in   5.036201s
# 
# RubyComp finished at Tue Nov 11 13:29:36