From: dblack@...
Date: 2006-07-10T00:50:18+09:00
Subject: Re: renaming files randomly

Hi --

On Mon, 10 Jul 2006, ara.t.howard@noaa.gov wrote:

> On Mon, 10 Jul 2006 Ara.T.Howard@noaa.gov wrote:
>
>> this loop loses data
>> 
>> if
>>
>>  files = %w( a b c )
>> 
>> and
>>
>>  new_names = %w( c b a )
>> 
>> then the renaming order is
>>
>>  a -->> c
>>  b -->> b
>>  c -->> a
>> 
>> so
>>
>>  File.rename 'a', 'c'  # c is clobbered
>>  File.rename 'b', 'b'  # ok
>>  File.rename 'c', 'a'  # a is clobbered, new c is lost
>> 
>> at the end of the loop you'll have only files 'a' and 'b' and no error will
>> have been thrown.
>
> sorry - replace 'a b c' with '1 2 3' and 'c b a' with '3 2 1' - basically you
> lose data when the slides have numbered names to begin with, which i noticed
> because this is exactly how my slideshow software names it's slides!  ;-)

OK, then:

   new_names = [*0...files.size].map {|n| "MUNGED#{n}" }.sort_by { rand }

:-)


David

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