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<title>Class: Ankusa::Classifier</title>
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<div id="classHeader">
<table class="header-table">
<tr class="top-aligned-row">
<td><strong>Class</strong></td>
<td class="class-name-in-header">Ankusa::Classifier</td>
</tr>
<tr class="top-aligned-row">
<td><strong>In:</strong></td>
<td>
<a href="../../files/lib/ankusa/classifier_rb.html">
lib/ankusa/classifier.rb
</a>
<br />
</td>
</tr>
<tr class="top-aligned-row">
<td><strong>Parent:</strong></td>
<td>
Object
</td>
</tr>
</table>
</div>
<!-- banner header -->
<div id="bodyContent">
<div id="contextContent">
</div>
<div id="method-list">
<h3 class="section-bar">Methods</h3>
<div class="name-list">
<a href="#M000007">classifications</a>
<a href="#M000006">classify</a>
<a href="#M000008">get_word_probs</a>
<a href="#M000003">new</a>
<a href="#M000004">train</a>
<a href="#M000005">untrain</a>
</div>
</div>
</div>
<!-- if includes -->
<div id="section">
<div id="attribute-list">
<h3 class="section-bar">Attributes</h3>
<div class="name-list">
<table>
<tr class="top-aligned-row context-row">
<td class="context-item-name">classnames</td>
<td class="context-item-value"> [R] </td>
<td class="context-item-desc"></td>
</tr>
</table>
</div>
</div>
<!-- if method_list -->
<div id="methods">
<h3 class="section-bar">Public Class methods</h3>
<div id="method-M000003" class="method-detail">
<a name="M000003"></a>
<div class="method-heading">
<a href="#M000003" class="method-signature">
<span class="method-name">new</span><span class="method-args">(storage)</span>
</a>
</div>
<div class="method-description">
<p><a class="source-toggle" href="#"
onclick="toggleCode('M000003-source');return false;">[Source]</a></p>
<div class="method-source-code" id="M000003-source">
<pre>
<span class="ruby-comment cmt"># File lib/ankusa/classifier.rb, line 6</span>
<span class="ruby-keyword kw">def</span> <span class="ruby-identifier">initialize</span>(<span class="ruby-identifier">storage</span>)
<span class="ruby-ivar">@storage</span> = <span class="ruby-identifier">storage</span>
<span class="ruby-ivar">@storage</span>.<span class="ruby-identifier">init_tables</span>
<span class="ruby-ivar">@classnames</span> = <span class="ruby-ivar">@storage</span>.<span class="ruby-identifier">classnames</span>
<span class="ruby-keyword kw">end</span>
</pre>
</div>
</div>
</div>
<h3 class="section-bar">Public Instance methods</h3>
<div id="method-M000007" class="method-detail">
<a name="M000007"></a>
<div class="method-heading">
<a href="#M000007" class="method-signature">
<span class="method-name">classifications</span><span class="method-args">(text)</span>
</a>
</div>
<div class="method-description">
<p><a class="source-toggle" href="#"
onclick="toggleCode('M000007-source');return false;">[Source]</a></p>
<div class="method-source-code" id="M000007-source">
<pre>
<span class="ruby-comment cmt"># File lib/ankusa/classifier.rb, line 44</span>
<span class="ruby-keyword kw">def</span> <span class="ruby-identifier">classifications</span>(<span class="ruby-identifier">text</span>)
<span class="ruby-identifier">result</span> = <span class="ruby-constant">Hash</span>.<span class="ruby-identifier">new</span> <span class="ruby-value">0</span>
<span class="ruby-constant">TextHash</span>.<span class="ruby-identifier">new</span>(<span class="ruby-identifier">text</span>).<span class="ruby-identifier">each</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">word</span>, <span class="ruby-identifier">count</span><span class="ruby-operator">|</span>
<span class="ruby-identifier">probs</span> = <span class="ruby-identifier">get_word_probs</span>(<span class="ruby-identifier">word</span>)
<span class="ruby-ivar">@classnames</span>.<span class="ruby-identifier">each</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">k</span><span class="ruby-operator">|</span> <span class="ruby-identifier">result</span>[<span class="ruby-identifier">k</span>] <span class="ruby-operator">+=</span> (<span class="ruby-constant">Math</span>.<span class="ruby-identifier">log</span>(<span class="ruby-identifier">probs</span>[<span class="ruby-identifier">k</span>]) <span class="ruby-operator">*</span> <span class="ruby-identifier">count</span>) }
}
<span class="ruby-comment cmt"># add the prior and exponentiate</span>
<span class="ruby-ivar">@classnames</span>.<span class="ruby-identifier">each</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">k</span><span class="ruby-operator">|</span>
<span class="ruby-identifier">result</span>[<span class="ruby-identifier">k</span>] <span class="ruby-operator">+=</span> <span class="ruby-constant">Math</span>.<span class="ruby-identifier">log</span>(<span class="ruby-ivar">@storage</span>.<span class="ruby-identifier">get_doc_count</span>(<span class="ruby-identifier">k</span>).<span class="ruby-identifier">to_f</span> <span class="ruby-operator">/</span> <span class="ruby-ivar">@storage</span>.<span class="ruby-identifier">doc_count_total</span>.<span class="ruby-identifier">to_f</span>)
<span class="ruby-identifier">result</span>[<span class="ruby-identifier">k</span>] = <span class="ruby-constant">Math</span>.<span class="ruby-identifier">exp</span>(<span class="ruby-identifier">result</span>[<span class="ruby-identifier">k</span>])
}
<span class="ruby-comment cmt"># normalize to get probs</span>
<span class="ruby-identifier">sum</span> = <span class="ruby-identifier">result</span>.<span class="ruby-identifier">values</span>.<span class="ruby-identifier">inject</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">x</span>,<span class="ruby-identifier">y</span><span class="ruby-operator">|</span> <span class="ruby-identifier">x</span><span class="ruby-operator">+</span><span class="ruby-identifier">y</span> }
<span class="ruby-ivar">@classnames</span>.<span class="ruby-identifier">each</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">k</span><span class="ruby-operator">|</span> <span class="ruby-identifier">result</span>[<span class="ruby-identifier">k</span>] = <span class="ruby-identifier">result</span>[<span class="ruby-identifier">k</span>] <span class="ruby-operator">/</span> <span class="ruby-identifier">sum</span> }
<span class="ruby-identifier">result</span>
<span class="ruby-keyword kw">end</span>
</pre>
</div>
</div>
</div>
<div id="method-M000006" class="method-detail">
<a name="M000006"></a>
<div class="method-heading">
<a href="#M000006" class="method-signature">
<span class="method-name">classify</span><span class="method-args">(text)</span>
</a>
</div>
<div class="method-description">
<p><a class="source-toggle" href="#"
onclick="toggleCode('M000006-source');return false;">[Source]</a></p>
<div class="method-source-code" id="M000006-source">
<pre>
<span class="ruby-comment cmt"># File lib/ankusa/classifier.rb, line 39</span>
<span class="ruby-keyword kw">def</span> <span class="ruby-identifier">classify</span>(<span class="ruby-identifier">text</span>)
<span class="ruby-comment cmt"># return the most probable class</span>
<span class="ruby-identifier">classifications</span>(<span class="ruby-identifier">text</span>).<span class="ruby-identifier">sort_by</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">c</span><span class="ruby-operator">|</span> <span class="ruby-operator">-</span><span class="ruby-identifier">c</span>[<span class="ruby-value">1</span>] }.<span class="ruby-identifier">first</span>.<span class="ruby-identifier">first</span>
<span class="ruby-keyword kw">end</span>
</pre>
</div>
</div>
</div>
<div id="method-M000004" class="method-detail">
<a name="M000004"></a>
<div class="method-heading">
<a href="#M000004" class="method-signature">
<span class="method-name">train</span><span class="method-args">(klass, text) {|word, count if block_given?| ...}</span>
</a>
</div>
<div class="method-description">
<p>
text can be either an array of strings or a string klass is a symbol
</p>
<p><a class="source-toggle" href="#"
onclick="toggleCode('M000004-source');return false;">[Source]</a></p>
<div class="method-source-code" id="M000004-source">
<pre>
<span class="ruby-comment cmt"># File lib/ankusa/classifier.rb, line 14</span>
<span class="ruby-keyword kw">def</span> <span class="ruby-identifier">train</span>(<span class="ruby-identifier">klass</span>, <span class="ruby-identifier">text</span>)
<span class="ruby-identifier">th</span> = <span class="ruby-constant">TextHash</span>.<span class="ruby-identifier">new</span>(<span class="ruby-identifier">text</span>)
<span class="ruby-identifier">th</span>.<span class="ruby-identifier">each</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">word</span>, <span class="ruby-identifier">count</span><span class="ruby-operator">|</span>
<span class="ruby-ivar">@storage</span>.<span class="ruby-identifier">incr_word_count</span> <span class="ruby-identifier">klass</span>, <span class="ruby-identifier">word</span>, <span class="ruby-identifier">count</span>
<span class="ruby-keyword kw">yield</span> <span class="ruby-identifier">word</span>, <span class="ruby-identifier">count</span> <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">block_given?</span>
}
<span class="ruby-ivar">@storage</span>.<span class="ruby-identifier">incr_total_word_count</span> <span class="ruby-identifier">klass</span>, <span class="ruby-identifier">th</span>.<span class="ruby-identifier">word_count</span>
<span class="ruby-identifier">doccount</span> = (<span class="ruby-identifier">text</span>.<span class="ruby-identifier">kind_of?</span> <span class="ruby-constant">Array</span>) <span class="ruby-operator">?</span> <span class="ruby-identifier">text</span>.<span class="ruby-identifier">length</span> <span class="ruby-operator">:</span> <span class="ruby-value">1</span>
<span class="ruby-ivar">@storage</span>.<span class="ruby-identifier">incr_doc_count</span> <span class="ruby-identifier">klass</span>, <span class="ruby-identifier">doccount</span>
<span class="ruby-ivar">@classnames</span> <span class="ruby-operator"><<</span> <span class="ruby-identifier">klass</span> <span class="ruby-keyword kw">if</span> <span class="ruby-keyword kw">not</span> <span class="ruby-ivar">@classnames</span>.<span class="ruby-identifier">include?</span> <span class="ruby-identifier">klass</span>
<span class="ruby-keyword kw">end</span>
</pre>
</div>
</div>
</div>
<div id="method-M000005" class="method-detail">
<a name="M000005"></a>
<div class="method-heading">
<a href="#M000005" class="method-signature">
<span class="method-name">untrain</span><span class="method-args">(klass, text) {|word, count if block_given?| ...}</span>
</a>
</div>
<div class="method-description">
<p>
text can be either an array of strings or a string klass is a symbol
</p>
<p><a class="source-toggle" href="#"
onclick="toggleCode('M000005-source');return false;">[Source]</a></p>
<div class="method-source-code" id="M000005-source">
<pre>
<span class="ruby-comment cmt"># File lib/ankusa/classifier.rb, line 28</span>
<span class="ruby-keyword kw">def</span> <span class="ruby-identifier">untrain</span>(<span class="ruby-identifier">klass</span>, <span class="ruby-identifier">text</span>)
<span class="ruby-identifier">th</span> = <span class="ruby-constant">TextHash</span>.<span class="ruby-identifier">new</span>(<span class="ruby-identifier">text</span>)
<span class="ruby-identifier">th</span>.<span class="ruby-identifier">each</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">word</span>, <span class="ruby-identifier">count</span><span class="ruby-operator">|</span>
<span class="ruby-ivar">@storage</span>.<span class="ruby-identifier">incr_word_count</span> <span class="ruby-identifier">klass</span>, <span class="ruby-identifier">word</span>, <span class="ruby-operator">-</span><span class="ruby-identifier">count</span>
<span class="ruby-keyword kw">yield</span> <span class="ruby-identifier">word</span>, <span class="ruby-identifier">count</span> <span class="ruby-keyword kw">if</span> <span class="ruby-identifier">block_given?</span>
}
<span class="ruby-ivar">@storage</span>.<span class="ruby-identifier">incr_total_word_count</span> <span class="ruby-identifier">klass</span>, <span class="ruby-operator">-</span><span class="ruby-identifier">th</span>.<span class="ruby-identifier">word_count</span>
<span class="ruby-identifier">doccount</span> = (<span class="ruby-identifier">text</span>.<span class="ruby-identifier">kind_of?</span> <span class="ruby-constant">Array</span>) <span class="ruby-operator">?</span> <span class="ruby-identifier">text</span>.<span class="ruby-identifier">length</span> <span class="ruby-operator">:</span> <span class="ruby-value">1</span>
<span class="ruby-ivar">@storage</span>.<span class="ruby-identifier">incr_doc_count</span> <span class="ruby-identifier">klass</span>, <span class="ruby-operator">-</span><span class="ruby-identifier">doccount</span>
<span class="ruby-keyword kw">end</span>
</pre>
</div>
</div>
</div>
<h3 class="section-bar">Protected Instance methods</h3>
<div id="method-M000008" class="method-detail">
<a name="M000008"></a>
<div class="method-heading">
<a href="#M000008" class="method-signature">
<span class="method-name">get_word_probs</span><span class="method-args">(word)</span>
</a>
</div>
<div class="method-description">
<p><a class="source-toggle" href="#"
onclick="toggleCode('M000008-source');return false;">[Source]</a></p>
<div class="method-source-code" id="M000008-source">
<pre>
<span class="ruby-comment cmt"># File lib/ankusa/classifier.rb, line 65</span>
<span class="ruby-keyword kw">def</span> <span class="ruby-identifier">get_word_probs</span>(<span class="ruby-identifier">word</span>)
<span class="ruby-identifier">probs</span> = <span class="ruby-ivar">@storage</span>.<span class="ruby-identifier">get_word_counts</span>(<span class="ruby-identifier">word</span>)
<span class="ruby-ivar">@classnames</span>.<span class="ruby-identifier">each</span> { <span class="ruby-operator">|</span><span class="ruby-identifier">cn</span><span class="ruby-operator">|</span>
<span class="ruby-comment cmt"># use a laplacian smoother</span>
<span class="ruby-identifier">probs</span>[<span class="ruby-identifier">cn</span>] = (<span class="ruby-identifier">probs</span>[<span class="ruby-identifier">cn</span>] <span class="ruby-operator">+</span> <span class="ruby-value">1</span>).<span class="ruby-identifier">to_f</span> <span class="ruby-operator">/</span> (<span class="ruby-ivar">@storage</span>.<span class="ruby-identifier">get_total_word_count</span>(<span class="ruby-identifier">cn</span>) <span class="ruby-operator">+</span> <span class="ruby-value">1</span>).<span class="ruby-identifier">to_f</span>
}
<span class="ruby-identifier">probs</span>
<span class="ruby-keyword kw">end</span>
</pre>
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