From: Rick DeNatale <rick.denatale@...>
Date: 2006-09-04T23:43:23+09:00
Subject: Re: Ordered contrast for String or Array

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

> Well, I was surprised when I couldn't seem to find a standard String
> method for splitting a String into an array of single character
> strings.
>
> Thinking about it again, another way is
>
>    string.scan /./
>
> I haven't benchmarked the two though so I don't know which is faster.
> I guess that's a task for the to-do list.

It looks like unpack is a clear winner:
rick@frodo:~/rubyscripts$ cat benchstringsplit.rb
require 'benchmark'
include Benchmark

class String
        def to_chars_array_with_unpack
                unpack('a'*length)
        end

        def to_chars_array_with_scan
                scan /./
        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
        str += str
        end
end

rick@frodo:~/rubyscripts$ ruby benchstringsplit.rb
Rehearsal ----------------------------------------------------------------
unpack 130 character string    1.130000   0.010000   1.140000 (  1.139545)
scan 130 character string      2.590000   0.000000   2.590000 (  3.678513)
unpack 260 character string    1.100000   0.000000   1.100000 (  1.672301)
scan 260 character string      2.170000   0.000000   2.170000 (  2.850112)
unpack 520 character string    1.000000   0.000000   1.000000 (  1.808740)
scan 520 character string      2.230000   0.010000   2.240000 (  3.562964)
unpack 1040 character string   1.080000   0.000000   1.080000 (  2.122081)
scan 1040 character string     2.260000   0.000000   2.260000 (  3.962422)
unpack 2080 character string   1.020000   0.000000   1.020000 (  1.518132)
scan 2080 character string     2.120000   0.000000   2.120000 (  3.091133)
------------------------------------------------------ total: 16.720000sec

                                   user     system      total        real
unpack 130 character string    0.920000   0.000000   0.920000 (  1.348387)
scan 130 character string      2.200000   0.000000   2.200000 (  5.322029)
unpack 260 character string    0.990000   0.000000   0.990000 (  1.363863)
scan 260 character string      2.210000   0.020000   2.230000 (  3.426876)
unpack 520 character string    1.010000   0.000000   1.010000 (  1.761541)
scan 520 character string      2.140000   0.000000   2.140000 (  2.251753)
unpack 1040 character string   1.010000   0.000000   1.010000 (  1.136075)
scan 1040 character string     2.220000   0.000000   2.220000 (  2.373706)
unpack 2080 character string   1.000000   0.000000   1.000000 (  1.083459)
scan 2080 character string     2.130000   0.000000   2.130000 (  2.199584)

-- 
Rick DeNatale

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