From: Rick DeNatale <rick.denatale@...>
Date: 2006-09-04T23:52:49+09:00
Subject: Re: Ordered contrast for String or Array

On 9/4/06, Rick DeNatale <rick.denatale@gmail.com> wrote:

> It looks like unpack is a clear winner:

Then on second thought, it looks like the problem with scan was the
construction of the regex, although using scan without pre-compiling
the regex is about twice as slow as unpack, using scan with a
pre-compiled regexp looks like it's about 100 times faster!

rick@frodo:~/rubyscripts$ cat benchstringsplit.rb
require 'benchmark'
include Benchmark

class String
        To_chars_regex = Regexp.new('/./')

        def to_chars_array_with_unpack
                unpack('a'*length)
        end

        def to_chars_array_with_scan
                scan /./
        end

        def to_chars_array_with_scan_precomp
                scan To_chars_regex
        end
end

iterations = 100
str = "abcdefghijklmnopqrstuvwxyz" * 5
bmbm do | x |
        5.times do
        x.report("unpack #{str.length} character string") do
                iterations.times do
                        str.to_chars_array_with_unpack
                end
        end

        x.report("scan #{str.length} character string") do
                iterations.times do
                        str.to_chars_array_with_scan
                end
        end

        x.report("scan-precomp #{str.length} character string") do
                iterations.times do
                        str.to_chars_array_with_scan_precomp
                end
        end
        str += str
        end
end


rick@frodo:~/rubyscripts$ ruby benchstringsplit.rb
Rehearsal ----------------------------------------------------------------------
unpack 130 character string          0.960000   0.010000   0.970000 (  0.984373)
scan 130 character string            2.150000   0.000000   2.150000 (  2.178162)
scan-precomp 130 character string    0.010000   0.000000   0.010000 (  0.012862)
unpack 260 character string          0.910000   0.000000   0.910000 (  0.910658)
scan 260 character string            2.040000   0.000000   2.040000 (  2.100734)
scan-precomp 260 character string    0.010000   0.000000   0.010000 (  0.010890)
unpack 520 character string          0.940000   0.000000   0.940000 (  0.942446)
scan 520 character string            1.990000   0.000000   1.990000 (  2.020499)
scan-precomp 520 character string    0.010000   0.000000   0.010000 (  0.010869)
unpack 1040 character string         0.980000   0.010000   0.990000 (  0.995709)
scan 1040 character string           2.140000   0.000000   2.140000 (  2.160120)
scan-precomp 1040 character string   0.010000   0.000000   0.010000 (  0.013315)
unpack 2080 character string         1.130000   0.000000   1.130000 (  1.214512)
scan 2080 character string           2.110000   0.000000   2.110000 (  2.132072)
scan-precomp 2080 character string   0.010000   0.000000   0.010000 (  0.011119)
------------------------------------------------------------ total: 15.420000sec

                                         user     system      total        real
unpack 130 character string          1.270000   0.000000   1.270000 (  1.338689)
scan 130 character string            2.530000   0.000000   2.530000 (  2.710398)
scan-precomp 130 character string    0.010000   0.000000   0.010000 (  0.011328)
unpack 260 character string          1.350000   0.000000   1.350000 (  1.445329)
scan 260 character string            2.420000   0.000000   2.420000 (  2.532545)
scan-precomp 260 character string    0.000000   0.000000   0.000000 (  0.010712)
unpack 520 character string          1.080000   0.010000   1.090000 (  1.086219)
scan 520 character string            2.120000   0.000000   2.120000 (  2.128990)
scan-precomp 520 character string    0.010000   0.000000   0.010000 (  0.010815)
unpack 1040 character string         1.080000   0.000000   1.080000 (  1.078558)
scan 1040 character string           2.120000   0.000000   2.120000 (  2.129707)
scan-precomp 1040 character string   0.010000   0.000000   0.010000 (  0.010945)
unpack 2080 character string         1.210000   0.000000   1.210000 (  1.267488)
scan 2080 character string           2.460000   0.000000   2.460000 (  2.627165)
scan-precomp 2080 character string   0.010000   0.000000   0.010000 (  0.012961)
-- 
Rick DeNatale

My blog on Ruby
http://talklikeaduck.denhaven2.com/