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| <div class="subTitle">org.apache.mahout.cf.taste.impl.similarity</div> |
| <h2 title="Class GenericItemSimilarity" class="title">Class GenericItemSimilarity</h2> |
| </div> |
| <div class="contentContainer"> |
| <ul class="inheritance"> |
| <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>org.apache.mahout.cf.taste.impl.similarity.GenericItemSimilarity</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/similarity/ItemSimilarity.html" title="interface in org.apache.mahout.cf.taste.similarity">ItemSimilarity</a></dd> |
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| <pre>public final class <span class="typeNameLabel">GenericItemSimilarity</span> |
| extends <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> |
| implements <a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html" title="interface in org.apache.mahout.cf.taste.similarity">ItemSimilarity</a></pre> |
| <div class="block"><p> |
| A "generic" <a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html" title="interface in org.apache.mahout.cf.taste.similarity"><code>ItemSimilarity</code></a> which takes a static list of precomputed item similarities and bases its |
| responses on that alone. The values may have been precomputed offline by another process, stored in a file, |
| and then read and fed into an instance of this class. |
| </p> |
| |
| <p> |
| This is perhaps the best <a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html" title="interface in org.apache.mahout.cf.taste.similarity"><code>ItemSimilarity</code></a> to use with |
| <a href="../../../../../../../org/apache/mahout/cf/taste/impl/recommender/GenericItemBasedRecommender.html" title="class in org.apache.mahout.cf.taste.impl.recommender"><code>GenericItemBasedRecommender</code></a>, for now, since the point |
| of item-based recommenders is that they can take advantage of the fact that item similarity is relatively |
| static, can be precomputed, and then used in computation to gain a significant performance advantage. |
| </p></div> |
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| <caption><span>Nested Classes</span><span class="tabEnd"> </span></caption> |
| <tr> |
| <th class="colFirst" scope="col">Modifier and Type</th> |
| <th class="colLast" scope="col">Class and Description</th> |
| </tr> |
| <tr class="altColor"> |
| <td class="colFirst"><code>static class </code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.ItemItemSimilarity.html" title="class in org.apache.mahout.cf.taste.impl.similarity">GenericItemSimilarity.ItemItemSimilarity</a></span></code> |
| <div class="block">Encapsulates a similarity between two items.</div> |
| </td> |
| </tr> |
| </table> |
| </li> |
| </ul> |
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| <h3>Constructor Summary</h3> |
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| <caption><span>Constructors</span><span class="tabEnd"> </span></caption> |
| <tr> |
| <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/similarity/GenericItemSimilarity.html#GenericItemSimilarity-org.apache.mahout.cf.taste.similarity.ItemSimilarity-org.apache.mahout.cf.taste.model.DataModel-">GenericItemSimilarity</a></span>(<a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html" title="interface in org.apache.mahout.cf.taste.similarity">ItemSimilarity</a> otherSimilarity, |
| <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html" title="interface in org.apache.mahout.cf.taste.model">DataModel</a> dataModel)</code> |
| <div class="block"> |
| Builds a list of item-item similarities given an <a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html" title="interface in org.apache.mahout.cf.taste.similarity"><code>ItemSimilarity</code></a> implementation and a |
| <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html" title="interface in org.apache.mahout.cf.taste.model"><code>DataModel</code></a>, rather than a list of <a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.ItemItemSimilarity.html" title="class in org.apache.mahout.cf.taste.impl.similarity"><code>GenericItemSimilarity.ItemItemSimilarity</code></a>s.</div> |
| </td> |
| </tr> |
| <tr class="rowColor"> |
| <td class="colOne"><code><span class="memberNameLink"><a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.html#GenericItemSimilarity-org.apache.mahout.cf.taste.similarity.ItemSimilarity-org.apache.mahout.cf.taste.model.DataModel-int-">GenericItemSimilarity</a></span>(<a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html" title="interface in org.apache.mahout.cf.taste.similarity">ItemSimilarity</a> otherSimilarity, |
| <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html" title="interface in org.apache.mahout.cf.taste.model">DataModel</a> dataModel, |
| int maxToKeep)</code> |
| <div class="block"> |
| Like <a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.html#GenericItemSimilarity-org.apache.mahout.cf.taste.similarity.ItemSimilarity-org.apache.mahout.cf.taste.model.DataModel-"><code>GenericItemSimilarity(ItemSimilarity, DataModel)</code></a> )}, but will only keep the specified |
| number of similarities from the given <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html" title="interface in org.apache.mahout.cf.taste.model"><code>DataModel</code></a>.</div> |
| </td> |
| </tr> |
| <tr class="altColor"> |
| <td class="colOne"><code><span class="memberNameLink"><a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.html#GenericItemSimilarity-java.lang.Iterable-">GenericItemSimilarity</a></span>(<a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Iterable.html?is-external=true" title="class or interface in java.lang">Iterable</a><<a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.ItemItemSimilarity.html" title="class in org.apache.mahout.cf.taste.impl.similarity">GenericItemSimilarity.ItemItemSimilarity</a>> similarities)</code> |
| <div class="block"> |
| Creates a <a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.html" title="class in org.apache.mahout.cf.taste.impl.similarity"><code>GenericItemSimilarity</code></a> from a precomputed list of <a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.ItemItemSimilarity.html" title="class in org.apache.mahout.cf.taste.impl.similarity"><code>GenericItemSimilarity.ItemItemSimilarity</code></a>s.</div> |
| </td> |
| </tr> |
| <tr class="rowColor"> |
| <td class="colOne"><code><span class="memberNameLink"><a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.html#GenericItemSimilarity-java.lang.Iterable-int-">GenericItemSimilarity</a></span>(<a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Iterable.html?is-external=true" title="class or interface in java.lang">Iterable</a><<a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.ItemItemSimilarity.html" title="class in org.apache.mahout.cf.taste.impl.similarity">GenericItemSimilarity.ItemItemSimilarity</a>> similarities, |
| int maxToKeep)</code> |
| <div class="block"> |
| Like <a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.html#GenericItemSimilarity-java.lang.Iterable-"><code>GenericItemSimilarity(Iterable)</code></a>, but will only keep the specified number of similarities |
| from the given <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Iterable.html?is-external=true" title="class or interface in java.lang"><code>Iterable</code></a> of similarities.</div> |
| </td> |
| </tr> |
| </table> |
| </li> |
| </ul> |
| <!-- ========== METHOD SUMMARY =========== --> |
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| <h3>Method Summary</h3> |
| <table class="memberSummary" border="0" cellpadding="3" cellspacing="0" summary="Method Summary table, listing methods, and an explanation"> |
| <caption><span id="t0" class="activeTableTab"><span>All Methods</span><span class="tabEnd"> </span></span><span id="t2" class="tableTab"><span><a href="javascript:show(2);">Instance Methods</a></span><span class="tabEnd"> </span></span><span id="t4" class="tableTab"><span><a href="javascript:show(8);">Concrete Methods</a></span><span class="tabEnd"> </span></span></caption> |
| <tr> |
| <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>long[]</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.html#allSimilarItemIDs-long-">allSimilarItemIDs</a></span>(long itemID)</code> </td> |
| </tr> |
| <tr id="i1" class="rowColor"> |
| <td class="colFirst"><code>double[]</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.html#itemSimilarities-long-long:A-">itemSimilarities</a></span>(long itemID1, |
| long[] itemID2s)</code> |
| <div class="block">A bulk-get version of <a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html#itemSimilarity-long-long-"><code>ItemSimilarity.itemSimilarity(long, long)</code></a>.</div> |
| </td> |
| </tr> |
| <tr id="i2" class="altColor"> |
| <td class="colFirst"><code>double</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.html#itemSimilarity-long-long-">itemSimilarity</a></span>(long itemID1, |
| long itemID2)</code> |
| <div class="block"> |
| Returns the similarity between two items.</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/similarity/GenericItemSimilarity.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><<a href="../../../../../../../org/apache/mahout/cf/taste/common/Refreshable.html" title="interface in org.apache.mahout.cf.taste.common">Refreshable</a>> alreadyRefreshed)</code> |
| <div class="block"> |
| Triggers "refresh" -- whatever that means -- of the implementation.</div> |
| </td> |
| </tr> |
| </table> |
| <ul class="blockList"> |
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| </a> |
| <h3>Methods inherited from class 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#toString--" title="class or interface in java.lang">toString</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> |
| </ul> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| </div> |
| <div class="details"> |
| <ul class="blockList"> |
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| <!-- ========= CONSTRUCTOR DETAIL ======== --> |
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| <li class="blockList"><a name="constructor.detail"> |
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| </a> |
| <h3>Constructor Detail</h3> |
| <a name="GenericItemSimilarity-java.lang.Iterable-"> |
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| </a> |
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| <h4>GenericItemSimilarity</h4> |
| <pre>public GenericItemSimilarity(<a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Iterable.html?is-external=true" title="class or interface in java.lang">Iterable</a><<a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.ItemItemSimilarity.html" title="class in org.apache.mahout.cf.taste.impl.similarity">GenericItemSimilarity.ItemItemSimilarity</a>> similarities)</pre> |
| <div class="block"><p> |
| Creates a <a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.html" title="class in org.apache.mahout.cf.taste.impl.similarity"><code>GenericItemSimilarity</code></a> from a precomputed list of <a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.ItemItemSimilarity.html" title="class in org.apache.mahout.cf.taste.impl.similarity"><code>GenericItemSimilarity.ItemItemSimilarity</code></a>s. Each |
| represents the similarity between two distinct items. Since similarity is assumed to be symmetric, it is |
| not necessary to specify similarity between item1 and item2, and item2 and item1. Both are the same. It |
| is also not necessary to specify a similarity between any item and itself; these are assumed to be 1.0. |
| </p> |
| |
| <p> |
| Note that specifying a similarity between two items twice is not an error, but, the later value will win. |
| </p></div> |
| <dl> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>similarities</code> - set of <a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.ItemItemSimilarity.html" title="class in org.apache.mahout.cf.taste.impl.similarity"><code>GenericItemSimilarity.ItemItemSimilarity</code></a>s on which to base this instance</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="GenericItemSimilarity-java.lang.Iterable-int-"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>GenericItemSimilarity</h4> |
| <pre>public GenericItemSimilarity(<a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Iterable.html?is-external=true" title="class or interface in java.lang">Iterable</a><<a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.ItemItemSimilarity.html" title="class in org.apache.mahout.cf.taste.impl.similarity">GenericItemSimilarity.ItemItemSimilarity</a>> similarities, |
| int maxToKeep)</pre> |
| <div class="block"><p> |
| Like <a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.html#GenericItemSimilarity-java.lang.Iterable-"><code>GenericItemSimilarity(Iterable)</code></a>, but will only keep the specified number of similarities |
| from the given <a href="http://docs.oracle.com/javase/7/docs/api/java/lang/Iterable.html?is-external=true" title="class or interface in java.lang"><code>Iterable</code></a> of similarities. It will keep those with the highest similarity -- those |
| that are therefore most important. |
| </p> |
| |
| <p> |
| Thanks to tsmorton for suggesting this and providing part of the implementation. |
| </p></div> |
| <dl> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>similarities</code> - set of <a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.ItemItemSimilarity.html" title="class in org.apache.mahout.cf.taste.impl.similarity"><code>GenericItemSimilarity.ItemItemSimilarity</code></a>s on which to base this instance</dd> |
| <dd><code>maxToKeep</code> - maximum number of similarities to keep</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="GenericItemSimilarity-org.apache.mahout.cf.taste.similarity.ItemSimilarity-org.apache.mahout.cf.taste.model.DataModel-"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>GenericItemSimilarity</h4> |
| <pre>public GenericItemSimilarity(<a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html" title="interface in org.apache.mahout.cf.taste.similarity">ItemSimilarity</a> otherSimilarity, |
| <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html" title="interface in org.apache.mahout.cf.taste.model">DataModel</a> dataModel) |
| 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"><p> |
| Builds a list of item-item similarities given an <a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html" title="interface in org.apache.mahout.cf.taste.similarity"><code>ItemSimilarity</code></a> implementation and a |
| <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html" title="interface in org.apache.mahout.cf.taste.model"><code>DataModel</code></a>, rather than a list of <a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.ItemItemSimilarity.html" title="class in org.apache.mahout.cf.taste.impl.similarity"><code>GenericItemSimilarity.ItemItemSimilarity</code></a>s. |
| </p> |
| |
| <p> |
| It's valid to build a <a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.html" title="class in org.apache.mahout.cf.taste.impl.similarity"><code>GenericItemSimilarity</code></a> this way, but perhaps missing some of the point of an |
| item-based recommender. Item-based recommenders use the assumption that item-item similarities are |
| relatively fixed, and might be known already independent of user preferences. Hence it is useful to |
| inject that information, using <a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.html#GenericItemSimilarity-java.lang.Iterable-"><code>GenericItemSimilarity(Iterable)</code></a>. |
| </p></div> |
| <dl> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>otherSimilarity</code> - other <a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html" title="interface in org.apache.mahout.cf.taste.similarity"><code>ItemSimilarity</code></a> to get similarities from</dd> |
| <dd><code>dataModel</code> - data model to get items from</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> items</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="GenericItemSimilarity-org.apache.mahout.cf.taste.similarity.ItemSimilarity-org.apache.mahout.cf.taste.model.DataModel-int-"> |
| <!-- --> |
| </a> |
| <ul class="blockListLast"> |
| <li class="blockList"> |
| <h4>GenericItemSimilarity</h4> |
| <pre>public GenericItemSimilarity(<a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html" title="interface in org.apache.mahout.cf.taste.similarity">ItemSimilarity</a> otherSimilarity, |
| <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html" title="interface in org.apache.mahout.cf.taste.model">DataModel</a> dataModel, |
| int maxToKeep) |
| 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"><p> |
| Like <a href="../../../../../../../org/apache/mahout/cf/taste/impl/similarity/GenericItemSimilarity.html#GenericItemSimilarity-org.apache.mahout.cf.taste.similarity.ItemSimilarity-org.apache.mahout.cf.taste.model.DataModel-"><code>GenericItemSimilarity(ItemSimilarity, DataModel)</code></a> )}, but will only keep the specified |
| number of similarities from the given <a href="../../../../../../../org/apache/mahout/cf/taste/model/DataModel.html" title="interface in org.apache.mahout.cf.taste.model"><code>DataModel</code></a>. It will keep those with the highest similarity |
| -- those that are therefore most important. |
| </p> |
| |
| <p> |
| Thanks to tsmorton for suggesting this and providing part of the implementation. |
| </p></div> |
| <dl> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>otherSimilarity</code> - other <a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html" title="interface in org.apache.mahout.cf.taste.similarity"><code>ItemSimilarity</code></a> to get similarities from</dd> |
| <dd><code>dataModel</code> - data model to get items from</dd> |
| <dd><code>maxToKeep</code> - maximum number of similarities to keep</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> items</dd> |
| </dl> |
| </li> |
| </ul> |
| </li> |
| </ul> |
| <!-- ============ METHOD DETAIL ========== --> |
| <ul class="blockList"> |
| <li class="blockList"><a name="method.detail"> |
| <!-- --> |
| </a> |
| <h3>Method Detail</h3> |
| <a name="itemSimilarity-long-long-"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>itemSimilarity</h4> |
| <pre>public double itemSimilarity(long itemID1, |
| long itemID2)</pre> |
| <div class="block"><p> |
| Returns the similarity between two items. Note that similarity is assumed to be symmetric, that |
| <code>itemSimilarity(item1, item2) == itemSimilarity(item2, item1)</code>, and that |
| <code>itemSimilarity(item1,item1) == 1.0</code> for all items. |
| </p></div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code><a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html#itemSimilarity-long-long-">itemSimilarity</a></code> in interface <code><a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html" title="interface in org.apache.mahout.cf.taste.similarity">ItemSimilarity</a></code></dd> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>itemID1</code> - first item</dd> |
| <dd><code>itemID2</code> - second item</dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>similarity between the two</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="itemSimilarities-long-long:A-"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>itemSimilarities</h4> |
| <pre>public double[] itemSimilarities(long itemID1, |
| long[] itemID2s)</pre> |
| <div class="block"><span class="descfrmTypeLabel">Description copied from interface: <code><a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html#itemSimilarities-long-long:A-">ItemSimilarity</a></code></span></div> |
| <div class="block"><p>A bulk-get version of <a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html#itemSimilarity-long-long-"><code>ItemSimilarity.itemSimilarity(long, long)</code></a>.</p></div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code><a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html#itemSimilarities-long-long:A-">itemSimilarities</a></code> in interface <code><a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html" title="interface in org.apache.mahout.cf.taste.similarity">ItemSimilarity</a></code></dd> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>itemID1</code> - first item ID</dd> |
| <dd><code>itemID2s</code> - second item IDs to compute similarity with</dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>similarity between itemID1 and other items</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="allSimilarItemIDs-long-"> |
| <!-- --> |
| </a> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <h4>allSimilarItemIDs</h4> |
| <pre>public long[] allSimilarItemIDs(long itemID)</pre> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code><a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html#allSimilarItemIDs-long-">allSimilarItemIDs</a></code> in interface <code><a href="../../../../../../../org/apache/mahout/cf/taste/similarity/ItemSimilarity.html" title="interface in org.apache.mahout.cf.taste.similarity">ItemSimilarity</a></code></dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>all IDs of similar items, in no particular order</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="refresh-java.util.Collection-"> |
| <!-- --> |
| </a> |
| <ul class="blockListLast"> |
| <li class="blockList"> |
| <h4>refresh</h4> |
| <pre>public void 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><<a href="../../../../../../../org/apache/mahout/cf/taste/common/Refreshable.html" title="interface in org.apache.mahout.cf.taste.common">Refreshable</a>> alreadyRefreshed)</pre> |
| <div class="block"><span class="descfrmTypeLabel">Description copied from interface: <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="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code><a href="../../../../../../../org/apache/mahout/cf/taste/common/Refreshable.html#refresh-java.util.Collection-">refresh</a></code> in interface <code><a href="../../../../../../../org/apache/mahout/cf/taste/common/Refreshable.html" title="interface in org.apache.mahout.cf.taste.common">Refreshable</a></code></dd> |
| <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> |
| </li> |
| </ul> |
| </li> |
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