1 | ###########################################################################
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2 | #
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3 | # BasClas.pm -- base class for all classifiers
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4 | #
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5 | # A component of the Greenstone digital library software
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6 | # from the New Zealand Digital Library Project at the
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7 | # University of Waikato, New Zealand.
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8 | #
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9 | # Copyright (C) 2000 New Zealand Digital Library Project
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10 | #
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11 | # This program is free software; you can redistribute it and/or modify
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12 | # it under the terms of the GNU General Public License as published by
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13 | # the Free Software Foundation; either version 2 of the License, or
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14 | # (at your option) any later version.
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15 | #
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16 | # This program is distributed in the hope that it will be useful,
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17 | # but WITHOUT ANY WARRANTY; without even the implied warranty of
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18 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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19 | # GNU General Public License for more details.
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20 | #
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21 | # You should have received a copy of the GNU General Public License
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22 | # along with this program; if not, write to the Free Software
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23 | # Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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24 | #
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25 | ###########################################################################
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26 |
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27 | package BasClas;
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28 |
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29 | # How a classifier works.
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30 | #
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31 | # For each classifier requested in the collect.cfg file, buildcol.pl creates
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32 | # a new classifier object (a subclass of BasClas). Later, it passes each
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33 | # document object to each classifier in turn for classification.
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34 | #
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35 | # Four primary functions are used:
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36 | #
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37 | # 1. "new" is called before the documents are processed to set up the
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38 | # classifier.
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39 | #
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40 | # 2. "init" is called after buildcol.pl has created the indexes etc but
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41 | # before the documents are classified in order that the classifier might
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42 | # set any variables it requires, etc.
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43 | #
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44 | # 3. "classify" is called once for each document object. The classifier
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45 | # "classifies" each document and updates its local data accordingly.
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46 | #
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47 | # 4. "get_classify_info" is called after every document has been
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48 | # classified. It collates the information about the documents and
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49 | # stores a reference to the classifier so that Greenstone can later
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50 | # display it.
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51 |
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52 | use parsargv;
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53 |
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54 | sub print_general_usage {
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55 | my ($plugin_name) = @_;
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56 | print STDERR "
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57 | -verbosity N Controls the quantity of output.
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58 | Defaults to verbosity of buildcol.pl, which is usually 2.
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59 |
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60 | (Most general classifier options are set internally by buildcol.)
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61 |
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62 | ";
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63 | }
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64 |
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65 | # print_usage should be overridden for any sub-classes
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66 | sub print_usage {
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67 | print STDERR "
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68 | This classifier has no classifier-specific options
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69 |
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70 | ";
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71 | }
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72 |
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73 | sub new {
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74 | my $class = shift (@_);
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75 | my $name = shift (@_);
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76 |
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77 | my $self = {};
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78 |
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79 | $self->{'outhandle'} = STDERR;
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80 |
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81 | # general options available to all classifiers
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82 | if (!parsargv::parse(\@_,
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83 | q^builddir/.*/^, \$self->{'builddir'},
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84 | q^outhandle/.*/STDERR^, \$self->{'outhandle'},
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85 | q^verbosity/\d/2^, \$self->{'verbosity'},
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86 | "allow_extra_options")) {
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87 |
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88 | print STDERR "\nThe $name classifier uses an incorrect general option\n";
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89 | print STDERR "(general options are those available to all classifiers).\n";
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90 | print STDERR "Check your collect.cfg configuration file.\n";
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91 | &print_general_usage($plugin_name);
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92 | die "\n";
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93 | }
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94 |
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95 |
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96 |
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97 | return bless $self, $class;
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98 | }
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99 |
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100 | sub init {
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101 | my $self = shift (@_);
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102 | }
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103 |
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104 | sub classify {
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105 | my $self = shift (@_);
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106 | my ($doc_obj) = @_;
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107 |
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108 | my $outhandle = $self->{'outhandle'};
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109 | print $outhandle "BasClas::classify function must be implemented in sub-class\n";
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110 | }
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111 |
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112 | sub get_classify_info {
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113 | my $self = shift (@_);
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114 |
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115 | my $outhandle = $self->{'outhandle'};
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116 | print $outhandle "BasClas::classify function must be implemented in sub-class\n";
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117 | }
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118 |
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119 | 1;
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