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hidden-lg"><div id="page-title"><h1>Reading Custom Events (Recommendation)</h1></div></div><div id="table-of-content-wrapper"><h5>On this page</h5><aside id="table-of-contents"><ul> <li> <a href="#add-the-custom-event">Add the Custom Event</a> </li> <li> <a href="#map-the-custom-event">Map the Custom Event</a> </li> </ul> </aside><hr/><a id="edit-page-link" href="https://github.com/apache/incubator-predictionio/tree/livedoc/docs/manual/source/templates/recommendation/reading-custom-events.html.md"><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>Reading Custom Events (Recommendation)</h1></div></div><div class="content"><p>You can modify the <a href="/templates/recommendation/dase/#data">default DataSource</a> to read</p> <ul> <li>Custom events other than the default <strong>rate</strong> and <strong>buy</strong> events.</li> <li>Events which involve different entity types other than the default <strong>user</strong> and <strong>item</strong>.</li> </ul> <h2 id='add-the-custom-event' class='header-anchors'>Add the Custom Event</h2><p>To read custom events, modify the function call <code>eventsDb.find()</code> in MyRecommendation/src/main/scala/<strong><em>DataSource.scala</em></strong>:</p> <ul> <li>Specify the names of events in <code>eventNames</code> parameters</li> <li>Specify the entity types involved in the events in the <code>entityType</code> and <code>targetEntityType</code> parameters accordingly</li> </ul> <p>In this example below, we modify DataSource to read custom <strong>like</strong> and <strong>dislike</strong> events where a customer likes or dislikes a product. The event has new entityType <strong>customer</strong> and targetEntityType <strong>product</strong>:</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
3
4
5
6
7</pre></td><td class="code"><pre><span class="k">val</span> <span class="n">eventsRDD</span><span class="k">:</span> <span class="kt">RDD</span><span class="o">[</span><span class="kt">Event</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="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">"customer"</span><span class="o">),</span> <span class="c1">// MODIFIED
</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">"like"</span><span class="o">,</span> <span class="s">"dislike"</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">"product"</span><span class="o">)))(</span><span class="n">sc</span><span class="o">)</span> <span class="c1">// MODIFIED
</span></pre></td></tr></tbody></table> </div> <h2 id='map-the-custom-event' class='header-anchors'>Map the Custom Event</h2><p>The ALS algorithm uses <code>Rating</code> object as input, so it is necessary to specify the mapping of your custom event to the Rating object. You can do so in MyRecommendation/src/main/scala/<strong><em>DataSource.scala</em></strong>.</p><p>To map <strong>like</strong> and <strong>dislike</strong> event to a Rating object with value of 4 and 1, respectively :</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
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22</pre></td><td class="code"><pre><span class="k">val</span> <span class="n">ratingsRDD</span><span class="k">:</span> <span class="kt">RDD</span><span class="o">[</span><span class="kt">Rating</span><span class="o">]</span> <span class="k">=</span> <span class="n">eventsRDD</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">rating</span> <span class="k">=</span> <span class="k">try</span> <span class="o">{</span>
        <span class="k">val</span> <span class="n">ratingValue</span><span class="k">:</span> <span class="kt">Double</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="c1">// MODIFIED
</span>          <span class="k">case</span> <span class="s">"like"</span> <span class="k">=&gt;</span> <span class="mf">4.0</span> <span class="c1">// map a like event to a rating of 4.0
</span>

          <span class="k">case</span> <span class="s">"dislike"</span> <span class="k">=&gt;</span> <span class="mf">1.0</span>  <span class="c1">// map a like event to a rating of 1.0
</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="c1">// entityId and targetEntityId is String
</span>        <span class="nc">Rating</span><span class="o">(</span><span class="n">event</span><span class="o">.</span><span class="n">entityId</span><span class="o">,</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">ratingValue</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 Rating. 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">rating</span>
    <span class="o">}</span>
</pre></td></tr></tbody></table> </div> <p>That&#39;s it! Your engine can read custom <strong>like</strong> and <strong>dislike</strong> event.</p><h4 id='<a-href="/templates/recommendation/customize-data-prep/">next:-customizing-data-preparator</a>' class='header-anchors' ><a href="/templates/recommendation/customize-data-prep/">Next: Customizing Data Preparator</a></h4></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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