= Fast Similar Files Finder

== Basics

=== Info

file-similars walks along the given dirs to find all similar files.

=== Description

file-similars will find all similar files, not only identical ones:
different version (.txt, .html, or .pdf) and different compression methods
(.zip, .gz, .tar.gz, .bip2), MP3 files with slightly different names or even
different sample rates, etc. It uses advanced soundex vector algorithm to
determine the file similarities.

The file similarity checking is extremely fast. It uses advanced soundex
vector algorithm to determine the similarity between files. Generally it
means that if there are n files, each having approximately m words in the
file name, the degree of calculation is merely

 O(n^2 * m)

regardless of file size. This is over hundreds times faster than any
existing file fingerprinting technology.

=== Files

link:release-log.txt[Release notes]. 

link:Changes[Changes logs]. 

== Help

The self-test output will help you understand what the module do and what
would you expect from the outcome.

  $ make test
  PERL_DL_NONLAZY=1 /usr/bin/perl "-Iblib/lib" "-Iblib/arch" test.pl
  1..4 todo 1;
  # Running under perl version 5.010000 for linux
  # Current time local: Fri Oct 31 12:31:40 2008
  # Current time GMT:   Fri Oct 31 16:31:40 2008
  # Using Test.pm version 1.25
  # Testing File::Find::Similars version 1.27
  
==== Testing 1, files under test/ subdir:
  
    9 test/(eBook) GNU - Python Standard Library 2001.pdf
    3 test/CardLayoutTest.java
    5 test/GNU - 2001 - Python Standard Library.pdf
    4 test/GNU - Python Standard Library (2001).rar
    9 test/LayoutTest.java
    3 test/PopupTest.java
    2 test/Python Standard Library.zip
    5 test/TestLayout.java
  ok 1 # (test.pl at line 55 TODO?!)
  
Note:
  
  - The file-similars script will pick out similar files from them in next test.
  - Let's assume that the number represent the file size in KB.
  
==== Testing 2 result should be:
  
  ## =========
             3 'CardLayoutTest.java' 'test/'
             5 'TestLayout.java' 'test/'
  
  ## =========
             4 'GNU - Python Standard Library (2001).rar' 'test/'
             5 'GNU - 2001 - Python Standard Library.pdf' 'test/'
  ok 2
  
Note:
  
  - There are 2 groups of similar files picked out by the script.
    The second group makes more sense.
  - The similar files are picked because their file names look similar.
  - However, the file size plays an important role as well.
  - There are 2 files in the second similar files group.
  - The file 'Python Standard Library.zip' is not considered to be similar to
    the group because its size is not similar to the group.
  
==== Testing 3, if Python.zip is bigger, result should be:
  
  ## =========
             3 'CardLayoutTest.java' 'test/'
             5 'TestLayout.java' 'test/'
  
  ## =========
             4 'Python Standard Library.zip' 'test/'
             4 'GNU - Python Standard Library (2001).rar' 'test/'
             5 'GNU - 2001 - Python Standard Library.pdf' 'test/'
  ok 3
  
Note:
  
  - There are 3 files in the second similar files group.
  - The file 'Python Standard Library.zip' is now in the 2nd similar files
    group because its size is now similar to the group.
  
==== Testing 4, if Python.zip is even bigger, result should be:
  
  ## =========
             3 'CardLayoutTest.java' 'test/'
             5 'TestLayout.java' 'test/'
  
  ## =========
             4 'GNU - Python Standard Library (2001).rar'       'test/'
             5 'GNU - 2001 - Python Standard Library.pdf'       'test/'
             6 'Python Standard Library.zip'                    'test/'
             9 '(eBook) GNU - Python Standard Library 2001.pdf' 'test/'
  ok 4
  
Note:
  
  - There are 4 files in the second similar files group.
  - The file 'Python Standard Library.zip' is still in the group.
  - But this time, because it is also considered to be similar to the .pdf
    file (since their size are now similar, 6 vs 9), a 4th file the .pdf
    is now included in the 2nd group.
  - If the size of file 'Python Standard Library.zip' is 12(KB), then the
    second similar files group will be split into two. Do you know why and
    which files each group will contain?

== Installation & Configuration

=== Installation

 perl Makefile.PL 
 make 
 make test
 make install

There includes in the package a client program called file-similars.
Copy it to a directory which is in the PATH. 

=== Get Help

Issue 'file-similars' to get help on how to use it. And also,

 perldoc File::Find::Similars

== Misc

link:Similars.why.htm[Why writting such tool; why it might be necessary].