array_order_2keys.rb

# Ruby 1.8.7
#                 user     system      total        real
# partition   0.180000   0.000000   0.180000 (  0.185015)
# sort_by     0.160000   0.010000   0.170000 (  0.160012)

# Ruby 1.9
#                 user     system      total        real
# partition   0.090000   0.000000   0.090000 (  0.092589)
# sort_by     0.160000   0.010000   0.170000 (  0.166785)


require 'benchmark'


number_of_people = 50000

Person = Struct.new(:emails, :publications)

people = []
number_of_people.times do |i|
  people << Person.new(rand(5), rand(10))
end

Benchmark.bm(10) do |benchmark|
  benchmark.report('partition') do
    people_with_emails, people_without_emails = people.partition { |person| person.emails.size > 0 }
    result = (people_with_emails + people_without_emails).sort { |a, b| a.publications <=> b.publications }
  end

  benchmark.report('sort_by') do
    people.sort_by { |person| [person.emails.size > 0 ? 1 : 0, person.publications] }
  end
end