NAME

File::FindSimilars - Fast similar-files finder

SYNOPSIS

  use File::FindSimilars;

  my $similars_finder = 
      File::FindSimilars->new( { fc_level => $fc_level, } );
  $similars_finder->find_for(\@ARGV);
  $similars_finder->similarity_check();

DESCRIPTION

Extremely fast file similarity checker. Similar-sized and similar-named files are picked out as suspicious candidates of duplicated files.

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)

which is over thousands times faster than any existing file fingerprinting technology.

ALGORITHM EXPLANATION

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..5 todo 2;
  # Running under perl version 5.010000 for linux
  # Current time local: Wed Nov  5 17:45:19 2008
  # Current time GMT:   Wed Nov  5 22:45:19 2008
  # Using Test.pm version 1.25
  # Testing File::FindSimilars version 2.04

  . . . .

  == Testing 2, files under test/ subdir:

    9 test/(eBook) GNU - Python Standard Library 2001.pdf
    3 test/Audio Book - The Grey Coloured Bunnie.mp3
    5 test/ColoredGrayBunny.ogg
    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
  ok 2 # (test.pl at line 83 TODO?!)

  Note:

  - The findsimilars script will pick out similar files from them in next test.
  - Let's assume that the number represent the file size in KB.

  == Testing 3 result should be:

  ## =========
             3 'Audio Book - The Grey Coloured Bunnie.mp3' 'test/'
             5 'ColoredGrayBunny.ogg'                      'test/'

  ## =========
             4 'GNU - Python Standard Library (2001).rar' 'test/'
             5 'GNU - 2001 - Python Standard Library.pdf' 'test/'
  ok 3

  Note:

  - There are 2 groups of similar files picked out by the script.
  - The similar files are picked because their file names look similar.
    Note that the first group looks different and spells differently too,
    which means that the script is versatile enough to handle file names that
    don't have space in it, and robust enough to deal with spelling mistakes.
  - Apart from the file name, the file size plays an important role as well.
  - There are 2 files in the second similar files group, the book 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 4, if Python.zip is bigger, result should be:

  ## =========
             3 'Audio Book - The Grey Coloured Bunnie.mp3' 'test/'
             5 'ColoredGrayBunny.ogg'                      'test/'

  ## =========
             4 'Python Standard Library.zip' 'test/'
             4 'GNU - Python Standard Library (2001).rar' 'test/'
             5 'GNU - 2001 - Python Standard Library.pdf' 'test/'
  ok 4

  Note:

  - There are now 3 files in the book files group.
  - The file 'Python Standard Library.zip' is included in the
    group because its size is now similar to the group.

  == Testing 5, if Python.zip is even bigger, result should be:

  ## =========
             3 'Audio Book - The Grey Coloured Bunnie.mp3' 'test/'
             5 'ColoredGrayBunny.ogg'                      '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 5

  Note:

  - There are 4 files in the book files group now.
  - 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 one
    is now included in the book group.
  - If the size of file 'Python Standard Library.zip' is 12(KB), then the
    book files group will be split into two. Do you know why and
    which files each group will contain?

The File::FindSimilars package comes with a fully functional demo script findsimilars. Please refer to its help file for further explanations.

This package is highly customizable. Refer to the class method new for details.

DEPENDS

This module depends on Text::Soundex, but not File::Find.

METHODS

File::FindSimilars->new(\%config_param)

Initialize the object.

  my $similars_finder = File::FindSimilars->new();

or,

  my $similars_finder = File::FindSimilars->new( {} );

which are the same as:

  my $similars_finder = File::FindSimilars->new( {
     soundex_weight => 50,      # percentage of weight that soundex takes,
                                # the rest is for file size
     fc_threshold => 75,        # over which files are considered similar
     delimiter => "\n## =========\n",   # delimiter between files output
     format => "%12d '%s' %s'%s'", # file info print format
     fc_level => 0,             # file comparison level
     verbose => 0,

  } );

What shown above are default settings. Any of the %config_param attribute can be omitted when calling the new method.

The new is the only class method. All the rest methods are object methods.