docs/0.13.0/api/docs/mahout-mr/org/apache/mahout/cf/taste/impl/recommender/ItemAverageRecommender.html - mahout - Git at Google

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 <div class="subTitle">org.apache.mahout.cf.taste.impl.recommender</div>
 <h2 title="Class ItemAverageRecommender" class="title">Class ItemAverageRecommender</h2>
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 <li><a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">java.lang.Object</a></li>
 <li>
 <ul class="inheritance">
 <li><a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/AbstractRecommender.html" title="class in org.apache.mahout.cf.taste.impl.recommender">org.apache.mahout.cf.taste.impl.recommender.AbstractRecommender</a></li>
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 <li>org.apache.mahout.cf.taste.impl.recommender.ItemAverageRecommender</li>
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 <dt>All Implemented Interfaces:</dt>
 <dd><a href="../../../../../../../org/apache/mahout/cf/taste/common/Refreshable.html" title="interface in org.apache.mahout.cf.taste.common">Refreshable</a>, <a href="../../../../../../../org/apache/mahout/cf/taste/recommender/Recommender.html" title="interface in org.apache.mahout.cf.taste.recommender">Recommender</a></dd>
 </dl>
 <hr>
 <br>
 <pre>public final class <span class="typeNameLabel">ItemAverageRecommender</span>
 extends <a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/AbstractRecommender.html" title="class in org.apache.mahout.cf.taste.impl.recommender">AbstractRecommender</a></pre>
 <div class="block"><p>
  A simple recommender that always estimates preference for an item to be the average of all known preference
  values for that item. No information about users is taken into account. This implementation is provided for
  experimentation; while simple and fast, it may not produce very good recommendations.
  </p></div>
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 <th class="colOne" scope="col">Constructor and Description</th>
 </tr>
 <tr class="altColor">
 <td class="colOne"><code><span class="memberNameLink"><a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/ItemAverageRecommender.html#ItemAverageRecommender-org.apache.mahout.cf.taste.model.DataModel-">ItemAverageRecommender</a></span>(<a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html" title="interface in org.apache.mahout.cf.taste.model">DataModel</a>&nbsp;dataModel)</code>&nbsp;</td>
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 <th class="colFirst" scope="col">Modifier and Type</th>
 <th class="colLast" scope="col">Method and Description</th>
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 <tr id="i0" class="altColor">
 <td class="colFirst"><code>float</code></td>
 <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/ItemAverageRecommender.html#estimatePreference-long-long-">estimatePreference</a></span>(long&nbsp;userID,
                   long&nbsp;itemID)</code>&nbsp;</td>
 </tr>
 <tr id="i1" class="rowColor">
 <td class="colFirst"><code><a href="http://docs.oracle.com/javase/7/docs/api/java/util/List.html?is-external=true" title="class or interface in java.util">List</a>&lt;<a href="../../../../../../../org/apache/mahout/cf/taste/recommender/RecommendedItem.html" title="interface in org.apache.mahout.cf.taste.recommender">RecommendedItem</a>&gt;</code></td>
 <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/ItemAverageRecommender.html#recommend-long-int-org.apache.mahout.cf.taste.recommender.IDRescorer-boolean-">recommend</a></span>(long&nbsp;userID,
          int&nbsp;howMany,
          <a href="../../../../../../../org/apache/mahout/cf/taste/recommender/IDRescorer.html" title="interface in org.apache.mahout.cf.taste.recommender">IDRescorer</a>&nbsp;rescorer,
          boolean&nbsp;includeKnownItems)</code>&nbsp;</td>
 </tr>
 <tr id="i2" class="altColor">
 <td class="colFirst"><code>void</code></td>
 <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/ItemAverageRecommender.html#refresh-java.util.Collection-">refresh</a></span>(<a href="http://docs.oracle.com/javase/7/docs/api/java/util/Collection.html?is-external=true" title="class or interface in java.util">Collection</a>&lt;<a href="../../../../../../../org/apache/mahout/cf/taste/common/Refreshable.html" title="interface in org.apache.mahout.cf.taste.common">Refreshable</a>&gt;&nbsp;alreadyRefreshed)</code>
 <div class="block">
  Triggers "refresh" -- whatever that means -- of the implementation.</div>
 </td>
 </tr>
 <tr id="i3" class="rowColor">
 <td class="colFirst"><code>void</code></td>
 <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/ItemAverageRecommender.html#removePreference-long-long-">removePreference</a></span>(long&nbsp;userID,
                 long&nbsp;itemID)</code>
 <div class="block">
  Default implementation which just calls <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html#removePreference-long-long-"><code>DataModel.removePreference(long, long)</code></a> (Object, Object)}.</div>
 </td>
 </tr>
 <tr id="i4" class="altColor">
 <td class="colFirst"><code>void</code></td>
 <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/ItemAverageRecommender.html#setPreference-long-long-float-">setPreference</a></span>(long&nbsp;userID,
              long&nbsp;itemID,
              float&nbsp;value)</code>
 <div class="block">
  Default implementation which just calls <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html#setPreference-long-long-float-"><code>DataModel.setPreference(long, long, float)</code></a>.</div>
 </td>
 </tr>
 <tr id="i5" class="rowColor">
 <td class="colFirst"><code><a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html?is-external=true" title="class or interface in java.lang">String</a></code></td>
 <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/ItemAverageRecommender.html#toString--">toString</a></span>()</code>&nbsp;</td>
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 <h3>Methods inherited from class&nbsp;org.apache.mahout.cf.taste.impl.recommender.<a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/AbstractRecommender.html" title="class in org.apache.mahout.cf.taste.impl.recommender">AbstractRecommender</a></h3>
 <code><a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/AbstractRecommender.html#getAllOtherItems-long-org.apache.mahout.cf.taste.model.PreferenceArray-boolean-">getAllOtherItems</a>, <a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/AbstractRecommender.html#getDataModel--">getDataModel</a>, <a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/AbstractRecommender.html#getDefaultCandidateItemsStrategy--">getDefaultCandidateItemsStrategy</a>, <a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/AbstractRecommender.html#recommend-long-int-">recommend</a>, <a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/AbstractRecommender.html#recommend-long-int-boolean-">recommend</a>, <a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/AbstractRecommender.html#recommend-long-int-org.apache.mahout.cf.taste.recommender.IDRescorer-">recommend</a></code></li>
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 <h3>Methods inherited from class&nbsp;java.lang.<a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">Object</a></h3>
 <code><a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html?is-external=true#clone--" title="class or interface in java.lang">clone</a>, <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html?is-external=true#equals-java.lang.Object-" title="class or interface in java.lang">equals</a>, <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html?is-external=true#finalize--" title="class or interface in java.lang">finalize</a>, <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html?is-external=true#getClass--" title="class or interface in java.lang">getClass</a>, <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html?is-external=true#hashCode--" title="class or interface in java.lang">hashCode</a>, <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html?is-external=true#notify--" title="class or interface in java.lang">notify</a>, <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html?is-external=true#notifyAll--" title="class or interface in java.lang">notifyAll</a>, <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html?is-external=true#wait--" title="class or interface in java.lang">wait</a>, <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html?is-external=true#wait-long-" title="class or interface in java.lang">wait</a>, <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html?is-external=true#wait-long-int-" title="class or interface in java.lang">wait</a></code></li>
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 <h4>ItemAverageRecommender</h4>
 <pre>public&nbsp;ItemAverageRecommender(<a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html" title="interface in org.apache.mahout.cf.taste.model">DataModel</a>&nbsp;dataModel)
                        throws <a href="../../../../../../../org/apache/mahout/cf/taste/common/TasteException.html" title="class in org.apache.mahout.cf.taste.common">TasteException</a></pre>
 <dl>
 <dt><span class="throwsLabel">Throws:</span></dt>
 <dd><code><a href="../../../../../../../org/apache/mahout/cf/taste/common/TasteException.html" title="class in org.apache.mahout.cf.taste.common">TasteException</a></code></dd>
 </dl>
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 <h3>Method Detail</h3>
 <a name="recommend-long-int-org.apache.mahout.cf.taste.recommender.IDRescorer-boolean-">
 <!--   -->
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 <ul class="blockList">
 <li class="blockList">
 <h4>recommend</h4>
 <pre>public&nbsp;<a href="http://docs.oracle.com/javase/7/docs/api/java/util/List.html?is-external=true" title="class or interface in java.util">List</a>&lt;<a href="../../../../../../../org/apache/mahout/cf/taste/recommender/RecommendedItem.html" title="interface in org.apache.mahout.cf.taste.recommender">RecommendedItem</a>&gt;&nbsp;recommend(long&nbsp;userID,
                                        int&nbsp;howMany,
                                        <a href="../../../../../../../org/apache/mahout/cf/taste/recommender/IDRescorer.html" title="interface in org.apache.mahout.cf.taste.recommender">IDRescorer</a>&nbsp;rescorer,
                                        boolean&nbsp;includeKnownItems)
                                 throws <a href="../../../../../../../org/apache/mahout/cf/taste/common/TasteException.html" title="class in org.apache.mahout.cf.taste.common">TasteException</a></pre>
 <dl>
 <dt><span class="paramLabel">Parameters:</span></dt>
 <dd><code>userID</code> - user for which recommendations are to be computed</dd>
 <dd><code>howMany</code> - desired number of recommendations</dd>
 <dd><code>rescorer</code> - rescoring function to apply before final list of recommendations is determined</dd>
 <dd><code>includeKnownItems</code> - whether to include items already known by the user in recommendations</dd>
 <dt><span class="returnLabel">Returns:</span></dt>
 <dd><a href="http://docs.oracle.com/javase/7/docs/api/java/util/List.html?is-external=true" title="class or interface in java.util"><code>List</code></a> of recommended <a href="../../../../../../../org/apache/mahout/cf/taste/recommender/RecommendedItem.html" title="interface in org.apache.mahout.cf.taste.recommender"><code>RecommendedItem</code></a>s, ordered from most strongly recommend to
          least</dd>
 <dt><span class="throwsLabel">Throws:</span></dt>
 <dd><code><a href="../../../../../../../org/apache/mahout/cf/taste/common/TasteException.html" title="class in org.apache.mahout.cf.taste.common">TasteException</a></code> - if an error occurs while accessing the <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html" title="interface in org.apache.mahout.cf.taste.model"><code>DataModel</code></a></dd>
 </dl>
 </li>
 </ul>
 <a name="estimatePreference-long-long-">
 <!--   -->
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 <li class="blockList">
 <h4>estimatePreference</h4>
 <pre>public&nbsp;float&nbsp;estimatePreference(long&nbsp;userID,
                                 long&nbsp;itemID)
                          throws <a href="../../../../../../../org/apache/mahout/cf/taste/common/TasteException.html" title="class in org.apache.mahout.cf.taste.common">TasteException</a></pre>
 <dl>
 <dt><span class="paramLabel">Parameters:</span></dt>
 <dd><code>userID</code> - user ID whose preference is to be estimated</dd>
 <dd><code>itemID</code> - item ID to estimate preference for</dd>
 <dt><span class="returnLabel">Returns:</span></dt>
 <dd>an estimated preference if the user has not expressed a preference for the item, or else the
          user's actual preference for the item. If a preference cannot be estimated, returns
          <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Double.html?is-external=true#NaN" title="class or interface in java.lang"><code>Double.NaN</code></a></dd>
 <dt><span class="throwsLabel">Throws:</span></dt>
 <dd><code><a href="../../../../../../../org/apache/mahout/cf/taste/common/TasteException.html" title="class in org.apache.mahout.cf.taste.common">TasteException</a></code> - if an error occurs while accessing the <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html" title="interface in org.apache.mahout.cf.taste.model"><code>DataModel</code></a></dd>
 </dl>
 </li>
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 <!--   -->
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 <h4>setPreference</h4>
 <pre>public&nbsp;void&nbsp;setPreference(long&nbsp;userID,
                           long&nbsp;itemID,
                           float&nbsp;value)
                    throws <a href="../../../../../../../org/apache/mahout/cf/taste/common/TasteException.html" title="class in org.apache.mahout.cf.taste.common">TasteException</a></pre>
 <div class="block"><span class="descfrmTypeLabel">Description copied from class:&nbsp;<code><a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/AbstractRecommender.html#setPreference-long-long-float-">AbstractRecommender</a></code></span></div>
 <div class="block"><p>
  Default implementation which just calls <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html#setPreference-long-long-float-"><code>DataModel.setPreference(long, long, float)</code></a>.
  </p></div>
 <dl>
 <dt><span class="overrideSpecifyLabel">Specified by:</span></dt>
 <dd><code><a href="../../../../../../../org/apache/mahout/cf/taste/recommender/Recommender.html#setPreference-long-long-float-">setPreference</a></code>&nbsp;in interface&nbsp;<code><a href="../../../../../../../org/apache/mahout/cf/taste/recommender/Recommender.html" title="interface in org.apache.mahout.cf.taste.recommender">Recommender</a></code></dd>
 <dt><span class="overrideSpecifyLabel">Overrides:</span></dt>
 <dd><code><a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/AbstractRecommender.html#setPreference-long-long-float-">setPreference</a></code>&nbsp;in class&nbsp;<code><a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/AbstractRecommender.html" title="class in org.apache.mahout.cf.taste.impl.recommender">AbstractRecommender</a></code></dd>
 <dt><span class="paramLabel">Parameters:</span></dt>
 <dd><code>userID</code> - user to set preference for</dd>
 <dd><code>itemID</code> - item to set preference for</dd>
 <dd><code>value</code> - preference value</dd>
 <dt><span class="throwsLabel">Throws:</span></dt>
 <dd><code><a href="../../../../../../../org/apache/mahout/cf/taste/common/TasteException.html" title="class in org.apache.mahout.cf.taste.common">TasteException</a></code> - if an error occurs while accessing the <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html" title="interface in org.apache.mahout.cf.taste.model"><code>DataModel</code></a></dd>
 </dl>
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 <h4>removePreference</h4>
 <pre>public&nbsp;void&nbsp;removePreference(long&nbsp;userID,
                              long&nbsp;itemID)
                       throws <a href="../../../../../../../org/apache/mahout/cf/taste/common/TasteException.html" title="class in org.apache.mahout.cf.taste.common">TasteException</a></pre>
 <div class="block"><span class="descfrmTypeLabel">Description copied from class:&nbsp;<code><a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/AbstractRecommender.html#removePreference-long-long-">AbstractRecommender</a></code></span></div>
 <div class="block"><p>
  Default implementation which just calls <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html#removePreference-long-long-"><code>DataModel.removePreference(long, long)</code></a> (Object, Object)}.
  </p></div>
 <dl>
 <dt><span class="overrideSpecifyLabel">Specified by:</span></dt>
 <dd><code><a href="../../../../../../../org/apache/mahout/cf/taste/recommender/Recommender.html#removePreference-long-long-">removePreference</a></code>&nbsp;in interface&nbsp;<code><a href="../../../../../../../org/apache/mahout/cf/taste/recommender/Recommender.html" title="interface in org.apache.mahout.cf.taste.recommender">Recommender</a></code></dd>
 <dt><span class="overrideSpecifyLabel">Overrides:</span></dt>
 <dd><code><a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/AbstractRecommender.html#removePreference-long-long-">removePreference</a></code>&nbsp;in class&nbsp;<code><a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/AbstractRecommender.html" title="class in org.apache.mahout.cf.taste.impl.recommender">AbstractRecommender</a></code></dd>
 <dt><span class="paramLabel">Parameters:</span></dt>
 <dd><code>userID</code> - user from which to remove preference</dd>
 <dd><code>itemID</code> - item for which to remove preference</dd>
 <dt><span class="throwsLabel">Throws:</span></dt>
 <dd><code><a href="../../../../../../../org/apache/mahout/cf/taste/common/TasteException.html" title="class in org.apache.mahout.cf.taste.common">TasteException</a></code> - if an error occurs while accessing the <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html" title="interface in org.apache.mahout.cf.taste.model"><code>DataModel</code></a></dd>
 </dl>
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 <a name="refresh-java.util.Collection-">
 <!--   -->
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 <ul class="blockList">
 <li class="blockList">
 <h4>refresh</h4>
 <pre>public&nbsp;void&nbsp;refresh(<a href="http://docs.oracle.com/javase/7/docs/api/java/util/Collection.html?is-external=true" title="class or interface in java.util">Collection</a>&lt;<a href="../../../../../../../org/apache/mahout/cf/taste/common/Refreshable.html" title="interface in org.apache.mahout.cf.taste.common">Refreshable</a>&gt;&nbsp;alreadyRefreshed)</pre>
 <div class="block"><span class="descfrmTypeLabel">Description copied from interface:&nbsp;<code><a href="../../../../../../../org/apache/mahout/cf/taste/common/Refreshable.html#refresh-java.util.Collection-">Refreshable</a></code></span></div>
 <div class="block"><p>
  Triggers "refresh" -- whatever that means -- of the implementation. The general contract is that any
  <a href="../../../../../../../org/apache/mahout/cf/taste/common/Refreshable.html" title="interface in org.apache.mahout.cf.taste.common"><code>Refreshable</code></a> should always leave itself in a consistent, operational state, and that the refresh
  atomically updates internal state from old to new.
  </p></div>
 <dl>
 <dt><span class="paramLabel">Parameters:</span></dt>
 <dd><code>alreadyRefreshed</code> - <a href="../../../../../../../org/apache/mahout/cf/taste/common/Refreshable.html" title="interface in org.apache.mahout.cf.taste.common"><code>Refreshable</code></a>s that are known to have already been
           refreshed as a result of an initial call to a {#refresh(Collection)} method on some
           object. This ensure that objects in a refresh dependency graph aren't refreshed twice
           needlessly.</dd>
 </dl>
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 <!--   -->
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 <h4>toString</h4>
 <pre>public&nbsp;<a href="http://docs.oracle.com/javase/7/docs/api/java/lang/String.html?is-external=true" title="class or interface in java.lang">String</a>&nbsp;toString()</pre>
 <dl>
 <dt><span class="overrideSpecifyLabel">Overrides:</span></dt>
 <dd><code><a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html?is-external=true#toString--" title="class or interface in java.lang">toString</a></code>&nbsp;in class&nbsp;<code><a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">Object</a></code></dd>
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