<!DOCTYPE html><html><head><title>Machine Learning With PredictionIO</title><meta charset="utf-8"/><meta content="IE=edge,chrome=1" http-equiv="X-UA-Compatible"/><meta name="viewport" content="width=device-width, initial-scale=1.0"/><meta class="swiftype" name="title" data-type="string" content="Machine Learning With PredictionIO"/><link rel="canonical" href="https://docs.prediction.io/demo/supervisedlearning/"/><link href="/images/favicon/normal-b330020a.png" rel="shortcut icon"/><link href="/images/favicon/apple-c0febcf2.png" rel="apple-touch-icon"/><link href="//fonts.googleapis.com/css?family=Open+Sans:300italic,400italic,600italic,700italic,800italic,400,300,600,700,800" rel="stylesheet"/><link href="//maxcdn.bootstrapcdn.com/font-awesome/4.2.0/css/font-awesome.min.css" rel="stylesheet"/><link href="/stylesheets/application-3598c7d7.css" rel="stylesheet" type="text/css"/><script src="//cdnjs.cloudflare.com/ajax/libs/html5shiv/3.7.2/html5shiv.min.js"></script><script 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href="/datacollection/analytics/"><span>Using Analytics Tools</span></a></li></ul></li><li class="level-1"><a class="expandible" href="#"><span>Choosing an Algorithm(s)</span></a><ul><li class="level-2"><a class="final" href="/algorithm/"><span>Built-in Algorithm Libraries</span></a></li><li class="level-2"><a class="final" href="/algorithm/switch/"><span>Switching to Another Algorithm</span></a></li><li class="level-2"><a class="final" href="/algorithm/multiple/"><span>Combining Multiple Algorithms</span></a></li><li class="level-2"><a class="final" href="/algorithm/custom/"><span>Adding Your Own Algorithms</span></a></li></ul></li><li class="level-1"><a class="expandible" href="#"><span>ML Tuning and Evaluation</span></a><ul><li class="level-2"><a class="final" href="/evaluation/"><span>Overview</span></a></li><li class="level-2"><a class="final" href="/evaluation/paramtuning/"><span>Hyperparameter Tuning</span></a></li><li class="level-2"><a class="final" href="/evaluation/evaluationdashboard/"><span>Evaluation Dashboard</span></a></li><li class="level-2"><a class="final" href="/evaluation/metricchoose/"><span>Choosing Evaluation Metrics</span></a></li><li class="level-2"><a class="final" href="/evaluation/metricbuild/"><span>Building Evaluation Metrics</span></a></li></ul></li><li class="level-1"><a class="expandible" href="#"><span>System Architecture</span></a><ul><li class="level-2"><a class="final" href="/system/"><span>Architecture Overview</span></a></li><li class="level-2"><a class="final" href="/system/anotherdatastore/"><span>Using Another Data Store</span></a></li></ul></li><li class="level-1"><a class="expandible" href="#"><span>Engine Template Gallery</span></a><ul><li class="level-2"><a class="final" href="http://templates.prediction.io"><span>Browse</span></a></li><li class="level-2"><a class="final" href="/community/submit-template/"><span>Submit your Engine as a Template</span></a></li></ul></li><li class="level-1"><a 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class="final" href="/community/projects/"><span>Community Projects</span></a></li></ul></li><li class="level-1"><a class="expandible" href="#"><span>Getting Help</span></a><ul><li class="level-2"><a class="final" href="/resources/faq/"><span>FAQs</span></a></li><li class="level-2"><a class="final" href="/support/"><span>Community Support</span></a></li><li class="level-2"><a class="final" href="/support/#enterprise-support"><span>Enterprise Support</span></a></li></ul></li><li class="level-1"><a class="expandible" href="#"><span>Resources</span></a><ul><li class="level-2"><a class="final" href="/resources/intellij/"><span>Developing Engines with IntelliJ IDEA</span></a></li><li class="level-2"><a class="final" href="/resources/upgrade/"><span>Upgrade Instructions</span></a></li><li class="level-2"><a class="final" href="/resources/glossary/"><span>Glossary</span></a></li></ul></li></ul></nav></div><div class="col-md-9 col-sm-12"><div class="content-header hidden-md hidden-lg"><div id="page-title"><h1>Machine Learning With PredictionIO</h1></div></div><div id="table-of-content-wrapper"><h5>On this page</h5><aside id="table-of-contents"><ul> <li> <a href="#introduction-to-supervised-learning">Introduction to Supervised Learning</a> </li> <li> <a href="#predictionio-and-supervised-learning">PredictionIO and Supervised Learning</a> </li> </ul> </aside><hr/><a id="edit-page-link" href="https://github.com/apache/incubator-predictionio/tree/livedoc/docs/manual/source/demo/supervisedlearning.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>Machine Learning With PredictionIO</h1></div></div><div class="content"><p>This guide is designed to give developers a brief introduction to fundamental concepts in machine learning, as well as an explanation of how these concept tie into PredictionIO&#39;s engine development platform. This particular guide will largely deal with giving some </p><h2 id='introduction-to-supervised-learning' class='header-anchors'>Introduction to Supervised Learning</h2><p>The first question we must ask is: what is machine learning? <strong>Machine learning</strong> is the field of study at the intersection of computer science, engineering, mathematics, and statistics which seeks to discover or infer patterns hidden within a set of observations, which we call our data. Some examples of problems that machine learning seeks to solve are:</p> <ul> <li>Predict whether a patient has breast cancer based on their mammogram results.</li> <li>Predict whether an e-mail is spam or not based on the e-mail&#39;s content.</li> <li>Predict today&#39;s temperature based on climate variables collected for the previous week.</li> </ul> <h3 id='thinking-about-data' class='header-anchors'>Thinking About Data</h3><p>In the latter examples, we are trying to predict an outcome \(Y\), or <strong>response</strong>, based on some recorded or observed variables \(X\), or <strong>features</strong>. For example: in the third problem each observation is a patient, the response variable \(Y\) is equal to 1 if this patient has breast cancer and 0 otherwise, and \(X\) represents the mammogram results. </p><p>When we say we want to predict \(Y\) using \(X\), we are trying to answer the question: how does a response \(Y\) depend on a set of features \(X\) affect the response \(Y\)? To do this we need a set of observations, which we call our <strong>training data</strong>, consisting of observations for which we have observed both \(Y\) and \(X\), in order to make inference about this relationship. </p><h3 id='different-types-of-supervised-learning-problems' class='header-anchors'>Different Types of Supervised Learning Problems</h3><p>Note that in the first two examples, the outcome \(Y\) can only take on two values (1 : cancer/spam, 0: no cancer/ no spam). Whenever the outcome variable \(Y\) denotes a label associated to a particular group of observations (i.e. cancer group), the <strong>supervised learning</strong> problem is also called a <strong>classification</strong> problem. In the third example, however, \(Y\) can take on any numerical value since it denotes some temperature reading (i.e. 25.143, 25.14233, 32.0). These types of supervised learning problems are also called <strong>regression</strong> problems.</p><h3 id='training-a-predictive-model' class='header-anchors'>Training a Predictive Model</h3><p>A predictive model should be thought of as a function \(f\) that takes as input a set of features, and outputs a predicted outcome (i.e. \(f(X) = Y\)). The phrase <strong>training a model</strong> simply refers to the process of using the training data to estimate such a function. </p><h2 id='predictionio-and-supervised-learning' class='header-anchors'>PredictionIO and Supervised Learning</h2><p>Machine learning methods generally assume that our observation responses and features are numeric vectors. We will say that observations in this format are in <strong>standard form</strong>. However, when you are working with real-life data this will often not be the case. The data will often be formatted in a manner that is specific to the application&#39;s needs. As an example, let&#39;s suppose our application is <a href="http://stackoverflow.com">StackOverFlow</a>. The data we want to analyze are questions, and we want to predict based on a question&#39;s content whether or not it is related to Scala. </p><p><strong>Self-check:</strong> Is this a classification or regression problem?</p><h3 id='thinking-about-data-with-predictionio' class='header-anchors'>Thinking About Data With PredictionIO</h3><p>PredictionIO&#39;s predictive engine development platform allows you to easily incorporate observations that are not in standard form. Continuing with our example, we can import the observations, or StackOverFlow questions, into <a href="/datacollection/">PredictionIO&#39;s Event Server</a> as events with the following properties:</p><p><code>properties = {question : String, topic : String}</code></p><p>The value <code>question</code> is the actual question stored as a <code>String</code>, and topic is also a string equal to either <code>&quot;Scala&quot;</code> or <code>&quot;Other&quot;</code>. Our outcome here is <code>topic</code>, and <code>question</code> will provide a source for extracting features. That is, we will be using <code>question</code> to predict the outcome <code>topic</code>.</p><p>Once the observations are loaded as events into the Event Server, the engine&#39;s <a href="/customize/">Data Source</a> component is able to read them, which allows you to treat them as objects in a Scala project. The engine&#39;s Preparator component is in charge of converting these observations into standard form. To do this, we can first map the topic values as follows:</p><p><code>Map(&quot;Other&quot; -&gt; 0, &quot;Scala&quot; -&gt; 1)</code>.</p><p>We can then vectorize the observation&#39;s associated question text to obtain a numeric feature vector for each of our observations. This text vectorization procedure is an example of a general concept in machine learning called <strong>feature extraction</strong>. After performing these transformations of our observations, they are now in standard form and can be used for training a large quantity of machine learning models.</p><h3 id='training-the-model-with-predictionio' class='header-anchors'>Training the Model With PredictionIO</h3><p>The Algorithm engine component serves two purposes: outputting a predictive model \(f\) and using this to predict the outcome variable. Here \(f\) takes as input a vectorized question and outputs either 0 or 1. However, our <code>Query</code> input will be again a question, and our <code>PredictedResult</code> the topic associated to the predicted label (0 or 1):</p><p><code>Query = {question : String}</code> <code>PredictedResult = {topic : String}</code></p><p>With PredictionIO&#39;s engine development platform, you can easily automate the vectorization of the Query question, as well as mapping the predicted label to the appropriate topic output format.</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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