From: "Shot (Piotr Szotkowski)" <shot@...>
Date: 2007-01-31T19:16:59+09:00
Subject: Benchmark results (was: Sane #hash implementation?)

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Mauricio Fernandez:

> (The order of the elements in Hash#to_a can change.)

Thanks for pointing this out, I fixed my specs and my code.

> Try this, it's O(n ln n) but actually works

Ok, I guess I have a question on what does exactly Benchmark results
mean. Doesn=E2=80=99t the below mean hash_map_sort is actually a bit slower=
 than
hash_sort?

Also, to ask two basic, follow-up questions: which Benchmark time is
the most significant one and is it more-or-less independent from other
system load? (I guess the two runs wouldn=E2=80=99t differ as much any of t=
he
times was other-load-independent=E2=80=A6)



$ cat block_hash.rb=20
require 'benchmark'
require 'set'

class Block < Set
  def hash_sort
    sort.hash
  end
  def hash_map_sort
    map {|a| a.hash}.sort.hash
  end
end

srand 1979
array =3D (0..1_000_000).sort_by {rand}

Benchmark.bmbm do |b|
  b.report 'hash_sort' do
    Block.new(array).hash_sort
  end
  b.report 'hash_map_sort' do
    Block.new(array).hash_map_sort
  end
end



$ ruby block_hash.rb=20
Rehearsal -------------------------------------------------
hash_sort       8.000000   1.366667   9.366667 (  6.208513)
hash_map_sort   9.750000   1.500000  11.250000 (  7.179749)
--------------------------------------- total: 20.616667sec

                    user     system      total        real
hash_sort       9.666667   1.100000  10.766667 (  6.677047)
hash_map_sort   9.566667   1.550000  11.116667 (  6.809388)



$ ruby block_hash.rb=20
Rehearsal -------------------------------------------------
hash_sort       8.133333   1.316667   9.450000 (  5.746571)
hash_map_sort   9.650000   1.766667  11.416667 (  7.065570)
--------------------------------------- total: 20.866667sec

                    user     system      total        real
hash_sort       9.316667   1.100000  10.416667 (  6.684088)
hash_map_sort   9.450000   1.566667  11.016667 (  6.796299)



-- Shot
--=20
It is a good morning exercise for a research scientist
to discard a pet hypothesis every day before breakfast.
It keeps him young.                    -- Konrad Lorenz

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