From: Robert Klemme <shortcutter@...>
Date: 2008-03-09T19:04:55+09:00
Subject: Re: duplicating characters in a string

On 08.03.2008 01:56, 7stud -- wrote:
> Robert Klemme wrote:
>> 2008/3/6, Joel VanderWerf <vjoel@path.berkeley.edu>:
>>>  It's only about a factor of two faster, according to the following, but
>>>  that matters sometimes.
>>
>>>  Rehearsal ---------------------------------------------------
>>>  s.gsub(re){...}   5.970000   0.000000   5.970000 (  6.009089)
>>>  s.gsub(re,...)    2.900000   0.060000   2.960000 (  3.148006)
>>>  ------------------------------------------ total: 8.930000sec
>>>
>>>                        user     system      total        real
>>>  s.gsub(re){...}   5.760000   0.010000   5.770000 (  5.925049)
>>>  s.gsub(re,...)    2.800000   0.060000   2.860000 (  2.914432)
>> What version did you test with? I get much more dramatic differences:
>>
>> 15:56:11 ~
>> $ ruby /c/Temp/gs.rb
>> Rehearsal -----------------------------------------------------------
>> s.gsub(re){|x| x * 2}    25.313000   0.031000  25.344000 ( 25.354000)
>> s.gsub(re){|x| x << x}   22.812000   0.000000  22.812000 ( 22.845000)
>> s.gsub(re, '\1\1')        6.516000   0.015000   6.531000 (  6.539000)
>> s.gsub(re, '\&\&')        6.578000   0.016000   6.594000 (  6.595000)
>> s.gsub(/./){|x| x * 2}   25.172000   0.016000  25.188000 ( 25.182000)
>> s.gsub(/./){|x| x << x}  22.843000   0.000000  22.843000 ( 22.857000)
>> s.gsub(/(.)/, '\1\1')     6.344000   0.015000   6.359000 (  6.355000)
>> s.gsub(/./, '\&\&')       6.188000   0.032000   6.220000 (  6.217000)
>> ------------------------------------------------ total: 121.891000sec
>>
>>                               user     system      total        real
>> s.gsub(re){|x| x * 2}    25.484000   0.015000  25.499000 ( 25.502000)
>> s.gsub(re){|x| x << x}   22.813000   0.031000  22.844000 ( 22.856000)
>> s.gsub(re, '\1\1')        6.312000   0.000000   6.312000 (  6.337000)
>> s.gsub(re, '\&\&')        6.359000   0.000000   6.359000 (  6.359000)
>> s.gsub(/./){|x| x * 2}   25.922000   0.000000  25.922000 ( 25.994000)
>> s.gsub(/./){|x| x << x}  22.672000   0.015000  22.687000 ( 22.707000)
>> s.gsub(/(.)/, '\1\1')     6.375000   0.016000   6.391000 (  6.389000)
>> s.gsub(/./, '\&\&')       6.235000   0.000000   6.235000 (  6.239000)
>> 16:00:22 ~
>> $ ruby -v
>> ruby 1.8.6 (2007-03-13 patchlevel 0) [i386-cygwin]
>> 16:00:26 ~
>> $ cat /c/Temp/gs.rb
>> require 'benchmark'
>>
>> s = ("abc" * 1_000_000).freeze
>> re = /(.)/
>> re2 = /./
>>
>> Benchmark.bmbm do |b|
>>   b.report("s.gsub(re){|x| x * 2}") do
>>     s.gsub(re) { |x| x * 2 }
>>   end
>>
>>   b.report("s.gsub(re){|x| x << x}") do
>>     s.gsub(re) { |x| x << x }
>>   end
>>
>>   b.report("s.gsub(re, '\\1\\1')") do
>>     s.gsub(re, "\\1\\1")
>>   end
>>
>>   b.report("s.gsub(re, '\\&\\&')") do
>>     s.gsub(re, "\\&\\&")
>>   end
>>
>>
>>   b.report("s.gsub(/./){|x| x * 2}") do
>>     s.gsub(/./) { |x| x * 2 }
>>   end
>>
>>   b.report("s.gsub(/./){|x| x << x}") do
>>     s.gsub(/./) { |x| x << x }
>>   end
>>
>>   b.report("s.gsub(/(.)/, '\\1\\1')") do
>>     s.gsub(/(.)/, "\\1\\1")
>>   end
>>
>>   b.report("s.gsub(/./, '\\&\\&')") do
>>     s.gsub(/./, "\\&\\&")
>>   end
>> end
>> 16:00:31 ~
>> $
> 
> And taking your non-perl champion:
> 
> s.gsub(/(.)/, '\1\1')
> 
> (I refuse to consider any code that uses perl syntax), and pitting it 
> against:

???  What exactly did you mean by the above text?

Cheers

	robert