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hidden-lg"><div id="page-title"><h1>Train with Rate Event (E-Commerce Recommendation)</h1></div></div><div id="table-of-content-wrapper"><h5>On this page</h5><aside id="table-of-contents"><ul> <li> <a href="#modification">Modification</a> </li> </ul> </aside><hr/><a id="edit-page-link" href="https://github.com/apache/incubator-predictionio/tree/livedoc/docs/manual/source/templates/ecommercerecommendation/train-with-rate-event.html.md.erb"><img src="/images/icons/edit-pencil-d6c1bb3d.png"/>Edit this page</a></div><div class="content-header hidden-sm hidden-xs"><div id="page-title"><h1>Train with Rate Event (E-Commerce Recommendation)</h1></div></div><div class="content"><p>This examples demonstrates how to modify E-Commerce Recommendation template to use &quot;rate&quot; event as Training Data.</p><p>However, recent &quot;view&quot; event is still used for recommendation for new user (to recommend items similar to what new user just recently viewed) and the returned scores are not predicted rating but a ranked scores for new user.</p><p>This template also supports that the user may rate same item multiple times and latest rating value will be used for training. The modification can be further simplified if the support of this case is not needed.</p><p>You can find the complete modified source code <a href="https://github.com/PredictionIO/PredictionIO/tree/develop/examples/scala-parallel-ecommercerecommendation/train-with-rate-event">here</a> and the modification is based on E-Commerce Recommendation template v0.1.1.</p><h2 id='modification' class='header-anchors'>Modification</h2><h3 id='datasource.scala' class='header-anchors'>DataSource.scala</h3><p>In DataSource, change <code>ViewEvent</code> case class to RateEvent. Add <code>rating: Double</code> is added to the RateEvent.</p><p>Change</p><div class="highlight scala"><table style="border-spacing: 0"><tbody><tr><td class="gutter gl" style="text-align: right"><pre class="lineno">1</pre></td><td class="code"><pre><span class="k">case</span> <span class="k">class</span> <span class="nc">ViewEvent</span><span class="o">(</span><span class="n">user</span><span class="k">:</span> <span class="kt">String</span><span class="o">,</span> <span class="n">item</span><span class="k">:</span> <span class="kt">String</span><span class="o">,</span> <span class="n">t</span><span class="k">:</span> <span class="kt">Long</span><span class="o">)</span>
</pre></td></tr></tbody></table> </div> <p>to</p><div class="highlight scala"><table style="border-spacing: 0"><tbody><tr><td class="gutter gl" style="text-align: right"><pre class="lineno">1
2</pre></td><td class="code"><pre><span class="c1">// MODIFIED
</span><span class="k">case</span> <span class="k">class</span> <span class="nc">RateEvent</span><span class="o">(</span><span class="n">user</span><span class="k">:</span> <span class="kt">String</span><span class="o">,</span> <span class="n">item</span><span class="k">:</span> <span class="kt">String</span><span class="o">,</span> <span class="n">rating</span><span class="k">:</span> <span class="kt">Double</span><span class="o">,</span> <span class="n">t</span><span class="k">:</span> <span class="kt">Long</span><span class="o">)</span>
</pre></td></tr></tbody></table> </div> <p>Modify TrainingData class to use rateEvent</p><div class="highlight scala"><table style="border-spacing: 0"><tbody><tr><td class="gutter gl" style="text-align: right"><pre class="lineno">1
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  <span class="k">val</span> <span class="n">users</span><span class="k">:</span> <span class="kt">RDD</span><span class="o">[(</span><span class="kt">String</span>, <span class="kt">User</span><span class="o">)],</span>
  <span class="k">val</span> <span class="n">items</span><span class="k">:</span> <span class="kt">RDD</span><span class="o">[(</span><span class="kt">String</span>, <span class="kt">Item</span><span class="o">)],</span>
  <span class="k">val</span> <span class="n">rateEvents</span><span class="k">:</span> <span class="kt">RDD</span><span class="o">[</span><span class="kt">RateEvent</span><span class="o">]</span> <span class="c1">// MODIFIED
</span><span class="o">)</span> <span class="k">extends</span> <span class="nc">Serializable</span> <span class="o">{</span>
  <span class="k">override</span> <span class="k">def</span> <span class="n">toString</span> <span class="k">=</span> <span class="o">{</span>
    <span class="n">s</span><span class="s">"users: [${users.count()} (${users.take(2).toList}...)]"</span> <span class="o">+</span>
    <span class="n">s</span><span class="s">"items: [${items.count()} (${items.take(2).toList}...)]"</span> <span class="o">+</span>
    <span class="c1">// MODIFIED
</span>    <span class="n">s</span><span class="s">"rateEvents: [${rateEvents.count()}] (${rateEvents.take(2).toList}...)"</span>
  <span class="o">}</span>
<span class="o">}</span>
</pre></td></tr></tbody></table> </div> <p>Modify <code>readTraining()</code> function of <code>DataSource</code> to read &quot;rate&quot; events (commented with &quot;// MODIFIED&quot;). Replace all <code>ViewEvent</code> with <code>RateEvent</code>. Replace all <code>viewEvent</code> with <code>rateEvent</code>. Retrieve the rating value from the event properties:</p><div class="highlight scala"><table style="border-spacing: 0"><tbody><tr><td class="gutter gl" style="text-align: right"><pre class="lineno">1
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  <span class="k">override</span>
  <span class="k">def</span> <span class="n">readTraining</span><span class="o">(</span><span class="n">sc</span><span class="k">:</span> <span class="kt">SparkContext</span><span class="o">)</span><span class="k">:</span> <span class="kt">TrainingData</span> <span class="o">=</span> <span class="o">{</span>
    <span class="k">val</span> <span class="n">eventsDb</span> <span class="k">=</span> <span class="nc">Storage</span><span class="o">.</span><span class="n">getPEvents</span><span class="o">()</span>

    <span class="o">....</span>

    <span class="c1">// get all "user" "rate" "item" events
</span>    <span class="k">val</span> <span class="n">rateEventsRDD</span><span class="k">:</span> <span class="kt">RDD</span><span class="o">[</span><span class="kt">RateEvent</span><span class="o">]</span> <span class="k">=</span> <span class="n">eventsDb</span><span class="o">.</span><span class="n">find</span><span class="o">(</span> <span class="c1">// MODIFIED
</span>      <span class="n">appId</span> <span class="k">=</span> <span class="n">dsp</span><span class="o">.</span><span class="n">appId</span><span class="o">,</span>
      <span class="n">entityType</span> <span class="k">=</span> <span class="nc">Some</span><span class="o">(</span><span class="s">"user"</span><span class="o">),</span>
      <span class="n">eventNames</span> <span class="k">=</span> <span class="nc">Some</span><span class="o">(</span><span class="nc">List</span><span class="o">(</span><span class="s">"rate"</span><span class="o">)),</span> <span class="c1">// MODIFIED
</span>      <span class="c1">// targetEntityType is optional field of an event.
</span>      <span class="n">targetEntityType</span> <span class="k">=</span> <span class="nc">Some</span><span class="o">(</span><span class="nc">Some</span><span class="o">(</span><span class="s">"item"</span><span class="o">)))(</span><span class="n">sc</span><span class="o">)</span>
      <span class="c1">// eventsDb.find() returns RDD[Event]
</span>      <span class="o">.</span><span class="n">map</span> <span class="o">{</span> <span class="n">event</span> <span class="k">=&gt;</span>
        <span class="k">val</span> <span class="n">rateEvent</span> <span class="k">=</span> <span class="k">try</span> <span class="o">{</span>
          <span class="n">event</span><span class="o">.</span><span class="n">event</span> <span class="k">match</span> <span class="o">{</span>
            <span class="k">case</span> <span class="s">"rate"</span> <span class="k">=&gt;</span> <span class="nc">RateEvent</span><span class="o">(</span> <span class="c1">// MODIFIED
</span>              <span class="n">user</span> <span class="k">=</span> <span class="n">event</span><span class="o">.</span><span class="n">entityId</span><span class="o">,</span>
              <span class="n">item</span> <span class="k">=</span> <span class="n">event</span><span class="o">.</span><span class="n">targetEntityId</span><span class="o">.</span><span class="n">get</span><span class="o">,</span>
              <span class="n">rating</span> <span class="k">=</span> <span class="n">event</span><span class="o">.</span><span class="n">properties</span><span class="o">.</span><span class="n">get</span><span class="o">[</span><span class="kt">Double</span><span class="o">](</span><span class="s">"rating"</span><span class="o">),</span> <span class="c1">// ADDED
</span>              <span class="n">t</span> <span class="k">=</span> <span class="n">event</span><span class="o">.</span><span class="n">eventTime</span><span class="o">.</span><span class="n">getMillis</span><span class="o">)</span>
            <span class="k">case</span> <span class="k">_</span> <span class="k">=&gt;</span> <span class="k">throw</span> <span class="k">new</span> <span class="nc">Exception</span><span class="o">(</span><span class="n">s</span><span class="s">"Unexpected event ${event} is read."</span><span class="o">)</span>
          <span class="o">}</span>
        <span class="o">}</span> <span class="k">catch</span> <span class="o">{</span>
          <span class="k">case</span> <span class="n">e</span><span class="k">:</span> <span class="kt">Exception</span> <span class="o">=&gt;</span> <span class="o">{</span>
            <span class="n">logger</span><span class="o">.</span><span class="n">error</span><span class="o">(</span><span class="n">s</span><span class="s">"Cannot convert ${event} to RateEvent."</span> <span class="o">+</span> <span class="c1">// MODIFIED
</span>              <span class="n">s</span><span class="s">" Exception: ${e}."</span><span class="o">)</span>
            <span class="k">throw</span> <span class="n">e</span>
          <span class="o">}</span>
        <span class="o">}</span>
        <span class="n">rateEvent</span>
      <span class="o">}.</span><span class="n">cache</span><span class="o">()</span>

    <span class="k">new</span> <span class="nc">TrainingData</span><span class="o">(</span>
      <span class="n">users</span> <span class="k">=</span> <span class="n">usersRDD</span><span class="o">,</span>
      <span class="n">items</span> <span class="k">=</span> <span class="n">itemsRDD</span><span class="o">,</span>
      <span class="n">rateEvents</span> <span class="k">=</span> <span class="n">rateEventsRDD</span> <span class="c1">// MODIFIED
</span>    <span class="o">)</span>

</pre></td></tr></tbody></table> </div> <h3 id='preparator.scala' class='header-anchors'>Preparator.scala</h3><p>Modify Preparator to pass rateEvents to algorithm as PreparedData (Replace all <code>ViewEvent</code> with <code>RateEvent</code>. Replace all <code>viewEvent</code> with <code>rateEvent</code>)</p><p>Modify Preparator&#39;s <code>parpare()</code> method:</p><div class="highlight scala"><table style="border-spacing: 0"><tbody><tr><td class="gutter gl" style="text-align: right"><pre class="lineno">1
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  <span class="o">...</span>

  <span class="k">def</span> <span class="n">prepare</span><span class="o">(</span><span class="n">sc</span><span class="k">:</span> <span class="kt">SparkContext</span><span class="o">,</span> <span class="n">trainingData</span><span class="k">:</span> <span class="kt">TrainingData</span><span class="o">)</span><span class="k">:</span> <span class="kt">PreparedData</span> <span class="o">=</span> <span class="o">{</span>
    <span class="k">new</span> <span class="nc">PreparedData</span><span class="o">(</span>
      <span class="n">users</span> <span class="k">=</span> <span class="n">trainingData</span><span class="o">.</span><span class="n">users</span><span class="o">,</span>
      <span class="n">items</span> <span class="k">=</span> <span class="n">trainingData</span><span class="o">.</span><span class="n">items</span><span class="o">,</span>
      <span class="n">rateEvents</span> <span class="k">=</span> <span class="n">trainingData</span><span class="o">.</span><span class="n">rateEvents</span><span class="o">)</span> <span class="c1">// MODIFIED
</span>  <span class="o">}</span>

  <span class="o">...</span>
</pre></td></tr></tbody></table> </div> <p>Modify <code>PreparedData</code> class:</p><div class="highlight scala"><table style="border-spacing: 0"><tbody><tr><td class="gutter gl" style="text-align: right"><pre class="lineno">1
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6</pre></td><td class="code"><pre><span class="k">class</span> <span class="nc">PreparedData</span><span class="o">(</span>
  <span class="k">val</span> <span class="n">users</span><span class="k">:</span> <span class="kt">RDD</span><span class="o">[(</span><span class="kt">String</span>, <span class="kt">User</span><span class="o">)],</span>
  <span class="k">val</span> <span class="n">items</span><span class="k">:</span> <span class="kt">RDD</span><span class="o">[(</span><span class="kt">String</span>, <span class="kt">Item</span><span class="o">)],</span>
  <span class="k">val</span> <span class="n">rateEvents</span><span class="k">:</span> <span class="kt">RDD</span><span class="o">[</span><span class="kt">RateEvent</span><span class="o">]</span> <span class="c1">// MODIFIED
</span><span class="o">)</span> <span class="k">extends</span> <span class="nc">Serializable</span>

</pre></td></tr></tbody></table> </div> <h3 id='ecommalgorithm.scala' class='header-anchors'>ECommAlgorithm.scala</h3><p>Modify <code>train()</code> method to train with rate event.</p><div class="highlight scala"><table style="border-spacing: 0"><tbody><tr><td class="gutter gl" style="text-align: right"><pre class="lineno">1
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  <span class="k">def</span> <span class="n">train</span><span class="o">(</span><span class="n">sc</span><span class="k">:</span> <span class="kt">SparkContext</span><span class="o">,</span> <span class="n">data</span><span class="k">:</span> <span class="kt">PreparedData</span><span class="o">)</span><span class="k">:</span> <span class="kt">ALSModel</span> <span class="o">=</span> <span class="o">{</span>
    <span class="n">require</span><span class="o">(!</span><span class="n">data</span><span class="o">.</span><span class="n">rateEvents</span><span class="o">.</span><span class="n">take</span><span class="o">(</span><span class="mi">1</span><span class="o">).</span><span class="n">isEmpty</span><span class="o">,</span> <span class="c1">// MODIFIED
</span>      <span class="n">s</span><span class="s">"rateEvents in PreparedData cannot be empty."</span> <span class="o">+</span> <span class="c1">// MODIFIED
</span>      <span class="s">" Please check if DataSource generates TrainingData"</span> <span class="o">+</span>
      <span class="s">" and Preprator generates PreparedData correctly."</span><span class="o">)</span>

    <span class="o">...</span>

    <span class="k">val</span> <span class="n">mllibRatings</span> <span class="k">=</span> <span class="n">data</span><span class="o">.</span><span class="n">rateEvents</span> <span class="c1">// MODIFIED
</span>      <span class="o">.</span><span class="n">map</span> <span class="o">{</span> <span class="n">r</span> <span class="k">=&gt;</span>
        <span class="o">...</span>

        <span class="o">((</span><span class="n">uindex</span><span class="o">,</span> <span class="n">iindex</span><span class="o">),</span> <span class="o">(</span><span class="n">r</span><span class="o">.</span><span class="n">rating</span><span class="o">,</span> <span class="n">r</span><span class="o">.</span><span class="n">t</span><span class="o">))</span> <span class="c1">// MODIFIED
</span>      <span class="o">}.</span><span class="n">filter</span> <span class="o">{</span> <span class="k">case</span> <span class="o">((</span><span class="n">u</span><span class="o">,</span> <span class="n">i</span><span class="o">),</span> <span class="n">v</span><span class="o">)</span> <span class="k">=&gt;</span>
        <span class="c1">// keep events with valid user and item index
</span>        <span class="o">(</span><span class="n">u</span> <span class="o">!=</span> <span class="o">-</span><span class="mi">1</span><span class="o">)</span> <span class="o">&amp;&amp;</span> <span class="o">(</span><span class="n">i</span> <span class="o">!=</span> <span class="o">-</span><span class="mi">1</span><span class="o">)</span>
      <span class="o">}.</span><span class="n">reduceByKey</span> <span class="o">{</span> <span class="k">case</span> <span class="o">(</span><span class="n">v1</span><span class="o">,</span> <span class="n">v2</span><span class="o">)</span> <span class="k">=&gt;</span> <span class="c1">// MODIFIED
</span>        <span class="c1">// if a user may rate same item with different value at different times,
</span>        <span class="c1">// use the latest value for this case.
</span>        <span class="c1">// Can remove this reduceByKey() if no need to support this case.
</span>        <span class="k">val</span> <span class="o">(</span><span class="n">rating1</span><span class="o">,</span> <span class="n">t1</span><span class="o">)</span> <span class="k">=</span> <span class="n">v1</span>
        <span class="k">val</span> <span class="o">(</span><span class="n">rating2</span><span class="o">,</span> <span class="n">t2</span><span class="o">)</span> <span class="k">=</span> <span class="n">v2</span>
        <span class="c1">// keep the latest value
</span>        <span class="k">if</span> <span class="o">(</span><span class="n">t1</span> <span class="o">&gt;</span> <span class="n">t2</span><span class="o">)</span> <span class="n">v1</span> <span class="k">else</span> <span class="n">v2</span>
      <span class="o">}</span>
      <span class="o">.</span><span class="n">map</span> <span class="o">{</span> <span class="k">case</span> <span class="o">((</span><span class="n">u</span><span class="o">,</span> <span class="n">i</span><span class="o">),</span> <span class="o">(</span><span class="n">rating</span><span class="o">,</span> <span class="n">t</span><span class="o">))</span> <span class="k">=&gt;</span> <span class="c1">// MODIFIED
</span>        <span class="c1">// MLlibRating requires integer index for user and item
</span>        <span class="nc">MLlibRating</span><span class="o">(</span><span class="n">u</span><span class="o">,</span> <span class="n">i</span><span class="o">,</span> <span class="n">rating</span><span class="o">)</span> <span class="c1">// MODIFIED
</span>      <span class="o">}.</span><span class="n">cache</span><span class="o">()</span>

    <span class="o">...</span>
  <span class="o">}</span>
</pre></td></tr></tbody></table> </div> <p>Modify <code>train()</code> method to use <code>ALS.trainImplicit()</code>:</p><p>Change the following from:</p><div class="highlight scala"><table style="border-spacing: 0"><tbody><tr><td class="gutter gl" style="text-align: right"><pre class="lineno">1
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    <span class="k">val</span> <span class="n">m</span> <span class="k">=</span> <span class="nc">ALS</span><span class="o">.</span><span class="n">trainImplicit</span><span class="o">(</span>
      <span class="n">ratings</span> <span class="k">=</span> <span class="n">mllibRatings</span><span class="o">,</span>
      <span class="n">rank</span> <span class="k">=</span> <span class="n">ap</span><span class="o">.</span><span class="n">rank</span><span class="o">,</span>
      <span class="n">iterations</span> <span class="k">=</span> <span class="n">ap</span><span class="o">.</span><span class="n">numIterations</span><span class="o">,</span>
      <span class="n">lambda</span> <span class="k">=</span> <span class="n">ap</span><span class="o">.</span><span class="n">lambda</span><span class="o">,</span>
      <span class="n">blocks</span> <span class="k">=</span> <span class="o">-</span><span class="mi">1</span><span class="o">,</span>
      <span class="n">alpha</span> <span class="k">=</span> <span class="mf">1.0</span><span class="o">,</span> <span class="c1">// WILL BE REMOVED
</span>      <span class="n">seed</span> <span class="k">=</span> <span class="n">seed</span><span class="o">)</span>
    <span class="o">...</span>

</pre></td></tr></tbody></table> </div> <p>to:</p><div class="highlight scala"><table style="border-spacing: 0"><tbody><tr><td class="gutter gl" style="text-align: right"><pre class="lineno">1
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    <span class="k">val</span> <span class="n">m</span> <span class="k">=</span> <span class="nc">ALS</span><span class="o">.</span><span class="n">train</span><span class="o">(</span> <span class="c1">// MODIFIED
</span>      <span class="n">ratings</span> <span class="k">=</span> <span class="n">mllibRatings</span><span class="o">,</span>
      <span class="n">rank</span> <span class="k">=</span> <span class="n">ap</span><span class="o">.</span><span class="n">rank</span><span class="o">,</span>
      <span class="n">iterations</span> <span class="k">=</span> <span class="n">ap</span><span class="o">.</span><span class="n">numIterations</span><span class="o">,</span>
      <span class="n">lambda</span> <span class="k">=</span> <span class="n">ap</span><span class="o">.</span><span class="n">lambda</span><span class="o">,</span>
      <span class="n">blocks</span> <span class="k">=</span> <span class="o">-</span><span class="mi">1</span><span class="o">,</span>
      <span class="n">seed</span> <span class="k">=</span> <span class="n">seed</span><span class="o">)</span>

    <span class="o">...</span>
</pre></td></tr></tbody></table> </div> <p>That&#39;s it! Now your engine can train model with rate events.</p></div></div></div></div><footer><div class="container"><div class="seperator"></div><div class="row"><div class="col-md-6 col-xs-6 footer-link-column"><div class="footer-link-column-row"><h4>Community</h4><ul><li><a href="//docs.prediction.io/install/" target="blank">Download</a></li><li><a href="//docs.prediction.io/" target="blank">Docs</a></li><li><a href="//github.com/apache/incubator-predictionio" target="blank">GitHub</a></li><li><a href="mailto:user-subscribe@predictionio.incubator.apache.org" target="blank">Subscribe to User Mailing List</a></li><li><a href="//stackoverflow.com/questions/tagged/predictionio" target="blank">Stackoverflow</a></li></ul></div></div><div class="col-md-6 col-xs-6 footer-link-column"><div class="footer-link-column-row"><h4>Contribute</h4><ul><li><a href="//predictionio.incubator.apache.org/community/contribute-code/" target="blank">Contribute</a></li><li><a href="//github.com/apache/incubator-predictionio" target="blank">Source Code</a></li><li><a href="//issues.apache.org/jira/browse/PIO" target="blank">Bug Tracker</a></li><li><a href="mailto:dev-subscribe@predictionio.incubator.apache.org" target="blank">Subscribe to Development Mailing List</a></li></ul></div></div></div></div><div id="footer-bottom"><div class="container"><div class="row"><div class="col-md-12"><div id="footer-logo-wrapper"><img alt="PredictionIO" src="/images/logos/logo-white-d1e9c6e6.png"/></div><div id="social-icons-wrapper"><a class="github-button" href="https://github.com/apache/incubator-predictionio" data-style="mega" data-count-href="/apache/incubator-predictionio/stargazers" data-count-api="/repos/apache/incubator-predictionio#stargazers_count" data-count-aria-label="# stargazers on GitHub" aria-label="Star apache/incubator-predictionio on GitHub">Star</a> <a class="github-button" href="https://github.com/apache/incubator-predictionio/fork" data-icon="octicon-git-branch" data-style="mega" data-count-href="/apache/incubator-predictionio/network" data-count-api="/repos/apache/incubator-predictionio#forks_count" data-count-aria-label="# forks on GitHub" aria-label="Fork apache/incubator-predictionio on GitHub">Fork</a> <script id="github-bjs" async="" defer="" src="https://buttons.github.io/buttons.js"></script><a href="//www.facebook.com/predictionio" target="blank"><img alt="PredictionIO on Twitter" src="/images/icons/twitter-ea9dc152.png"/></a> <a href="//twitter.com/predictionio" target="blank"><img alt="PredictionIO on Facebook" src="/images/icons/facebook-5c57939c.png"/></a> </div></div></div></div></div></footer></div><script>(function(w,d,t,u,n,s,e){w['SwiftypeObject']=n;w[n]=w[n]||function(){
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