From: Maciej Tomaka <lunatyq@...>
Date: 2008-07-30T18:24:41+09:00
Subject: Re: Interesting Array Initialization Typo

The correct benchmark is:
(look how long x.times takes :)
require 'benchmark'
include Benchmark

bmbm do |t|
    t.report("<<") do
        100_000.times do
            a = []
            a << [ 0,  1,  2,  3,  4,  5, 6,   7,  8,  9]
            a << [ 10, 11, 12, 13, 14, 15, 16, 17, 18, 19]
            a << [ 20, 21, 22, 23, 24, 25, 26, 27, 28, 29]
            a << [ 30, 31, 32, 33, 34, 35, 36, 37, 38, 39]
            a << [ 40, 41, 42, 43, 44, 45, 46, 47, 48, 49]
            a << [ 50, 51, 52, 53, 54, 55, 56, 57, 58, 59]
            a << [ 60, 61, 62, 63, 64, 65, 66, 67, 68, 69]
            a << [ 70, 71, 72, 73, 74, 75, 76, 77, 78, 79]
            a << [ 80, 81, 82, 83, 84, 85, 86, 87, 88, 89]
            a << [ 90, 91, 92, 93, 94, 95, 96, 97, 98, 99]
        end
    end

    t.report("[]") do
        100_000.times do
            a = [
              [ 0,  1,  2,  3,  4,  5, 6,   7,  8,  9],
              [ 10, 11, 12, 13, 14, 15, 16, 17, 18, 19],
              [ 20, 21, 22, 23, 24, 25, 26, 27, 28, 29],
              [ 30, 31, 32, 33, 34, 35, 36, 37, 38, 39],
              [ 40, 41, 42, 43, 44, 45, 46, 47, 48, 49],
              [ 50, 51, 52, 53, 54, 55, 56, 57, 58, 59],
              [ 60, 61, 62, 63, 64, 65, 66, 67, 68, 69],
              [ 70, 71, 72, 73, 74, 75, 76, 77, 78, 79],
              [ 80, 81, 82, 83, 84, 85, 86, 87, 88, 89],
              [ 90, 91, 92, 93, 94, 95, 96, 97, 98, 99]
            ]
        end
    end

    t.report("NO") do
        100_000.times do
            100.times do |x|
            end
        end
    end
end

Rehearsal --------------------------------------
<<   1.020000   0.020000   1.040000 (  1.047729)
[]   0.730000   0.010000   0.740000 (  0.741970)
NO   4.270000   1.510000   5.780000 (  5.808074)
----------------------------- total: 7.560000sec

         user     system      total        real
<<   1.000000   0.020000   1.020000 (  1.032165)
[]   0.740000   0.010000   0.750000 (  0.743470)
NO   5.070000   1.560000   6.630000 (  6.634026)

So << and [] are comparable.

Shadowfirebird has good solution inmho w/o significant perfomance 
impact.
-- 
Posted via http://www.ruby-forum.com/.