RePrec::Salton - compute precision values

RePrec documentation Contained in the RePrec distribution.

Index

Code Index:

NAME

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RePrec::Salton - compute precision values

SYNOPSIS

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See RePrec(3).

DESCRIPTION

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Compute precision values and interpolate according to Salton's proposal. Precision is not uniquely defined in the case of ranks which don't have relevant documents. Therefore it migth happen that for a given recaqll point more than one precision value is returned.

METHODS

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See RePrec(3).

Constructor.

BUGS

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Yes. Please let me know!

SEE ALSO

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RePrec(3), perl(1).

AUTHOR

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Norbert Gövert <goevert@ls6.cs.uni-dortmund.de>

RePrec documentation Contained in the RePrec distribution. 
###*###################### -*- Mode: Perl -*- #########################
##
## File          : $RCSfile: Salton.pm,v $
##
## Author        : Norbert Gövert
## Created On    : Wed Nov  1 17:43:53 2000
## Last Modified : Time-stamp: <2000-11-09 18:28:18 goevert>
##
## Description   : 
##
## $Id: Salton.pm,v 1.6 2003/06/13 12:29:30 goevert Exp $
##
######################################################################


use strict;




package RePrec::Salton;


use base qw(RePrec);


our $VERSION;
'$Name: release_0_32 $ 0_0' =~ /(\d+)[-_](\d+)/; $VERSION = sprintf '%d.%03d', $1, $2;


## public ############################################################


sub precision {

  my $self = shift;
  my @recall = @_;

  my @precision_rank = $self->precision_rank;

  my @result;

  foreach my $recall (sort @recall) {

    return undef unless defined $recall and $recall >= 0 and $recall <= 1;

    # interpolate precision
    my $precision = 0;
    foreach (reverse @precision_rank) {
      print STDERR "@$_\n";
      last if $_->[0] < $recall;
      $precision = $_->[1];
    }
    push @result, [ $recall, $precision ];
  }

  @result;
}


sub precision_rank {

  my $self = shift;

  my @result;
  foreach (@{$self->{rank_rels_nrels}}) {
    my $total = $_->[0] + $_->[1];
    my $recall = $_->[0] / $self->{rels};
    push @result, [ $recall, $_->[0] / $total ];
  }

  my $maxprec = 0;
  foreach (reverse @result) {
    if ($_->[1] < $maxprec) {
      $_->[1] = $maxprec;
    } else {
      $maxprec = $_->[1];
    }
  }

  @result;
}


## private ###########################################################




1;
__END__