versions/0.11.0/tutorials/scala/mnist.html

<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"/> <meta content="IE=edge" http-equiv="X-UA-Compatible"/> <meta content="width=device-width, initial-scale=1" name="viewport"/> <meta content="Handwritten Digit Recognition" property="og:title"> <meta content="https://raw.githubusercontent.com/dmlc/web-data/master/mxnet/image/og-logo.png" property="og:image"> <meta content="https://raw.githubusercontent.com/dmlc/web-data/master/mxnet/image/og-logo.png" property="og:image:secure_url"> <meta content="Handwritten Digit Recognition" property="og:description"/> <title>Handwritten Digit Recognition — mxnet documentation</title> <link crossorigin="anonymous" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css" integrity="sha384-1q8mTJOASx8j1Au+a5WDVnPi2lkFfwwEAa8hDDdjZlpLegxhjVME1fgjWPGmkzs7" rel="stylesheet"/> <link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.5.0/css/font-awesome.min.css" rel="stylesheet"/> <link href="../../_static/basic.css" rel="stylesheet" type="text/css"> <link href="../../_static/pygments.css" rel="stylesheet" type="text/css"> <link href="../../_static/mxnet.css" rel="stylesheet" type="text/css"/> <script type="text/javascript"> var DOCUMENTATION_OPTIONS = { URL_ROOT: '../../', VERSION: '', COLLAPSE_INDEX: false, FILE_SUFFIX: '.html', HAS_SOURCE: true, SOURCELINK_SUFFIX: '.txt' }; </script> <script src="https://code.jquery.com/jquery-1.11.1.min.js" type="text/javascript"></script> <script src="../../_static/underscore.js" type="text/javascript"></script> <script src="../../_static/searchtools_custom.js" type="text/javascript"></script> <script src="../../_static/doctools.js" type="text/javascript"></script> <script src="../../_static/selectlang.js" type="text/javascript"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML" type="text/javascript"></script> <script type="text/javascript"> jQuery(function() { Search.loadIndex("/versions/0.11.0/searchindex.js"); Search.init();}); </script>          <link href="../../genindex.html" rel="index" title="Index"> <link href="../../search.html" rel="search" title="Search"/> <link href="https://raw.githubusercontent.com/dmlc/web-data/master/mxnet/image/mxnet-icon.png" rel="icon" type="image/png"/> </link></link></link></meta></meta></meta></head> <body background="https://raw.githubusercontent.com/dmlc/web-data/master/mxnet/image/mxnet-background-compressed.jpeg" role="document"> <div class="content-block"><div class="navbar navbar-fixed-top"> <div class="container" id="navContainer"> <div class="innder" id="header-inner"> <h1 id="logo-wrap"> <a href="../../" id="logo"><img src="https://raw.githubusercontent.com/dmlc/web-data/master/mxnet/image/mxnet_logo.png"/></a> </h1> <nav class="nav-bar" id="main-nav"> <a class="main-nav-link" href="/versions/0.11.0/get_started/install.html">Install</a> <a aria-expanded="true" aria-haspopup="true" class="main-nav-link dropdown-toggle" data-toggle="dropdown" href="#" role="button">Gluon </a> <ul class="dropdown-menu navbar-menu" id="package-dropdown-menu"> <li><a class="main-nav-link" href="/versions/0.11.0/tutorials/gluon/gluon.html">About</a></li> <li><a class="main-nav-link" href="https://www.d2l.ai/">Dive into Deep Learning</a></li> <li><a class="main-nav-link" href="https://gluon-cv.mxnet.io">GluonCV Toolkit</a></li> <li><a class="main-nav-link" href="https://gluon-nlp.mxnet.io/">GluonNLP Toolkit</a></li> </ul> <a aria-expanded="true" aria-haspopup="true" class="main-nav-link dropdown-toggle" data-toggle="dropdown" href="#" role="button">API </a> <ul class="dropdown-menu navbar-menu" id="package-dropdown-menu"> <li><a class="main-nav-link" href="/versions/0.11.0/api/python/index.html">Python</a></li> <li><a class="main-nav-link" href="/versions/0.11.0/api/c++/index.html">C++</a></li> <li><a class="main-nav-link" href="/versions/0.11.0/api/julia/index.html">Julia</a></li> <li><a class="main-nav-link" href="/versions/0.11.0/api/perl/index.html">Perl</a></li> <li><a class="main-nav-link" href="/versions/0.11.0/api/r/index.html">R</a></li> <li><a class="main-nav-link" href="/versions/0.11.0/api/scala/index.html">Scala</a></li> </ul> <a aria-expanded="true" aria-haspopup="true" class="main-nav-link dropdown-toggle" data-toggle="dropdown" href="#" role="button">Docs </a> <ul class="dropdown-menu navbar-menu" id="package-dropdown-menu-docs"> <li><a class="main-nav-link" href="/versions/0.11.0/how_to/faq.html">FAQ</a></li> <li><a class="main-nav-link" href="/versions/0.11.0/tutorials/index.html">Tutorials</a> <li><a class="main-nav-link" href="https://github.com/apache/incubator-mxnet/tree/v0.11.0/example">Examples</a></li> <li><a class="main-nav-link" href="/versions/0.11.0/architecture/index.html">Architecture</a></li> <li><a class="main-nav-link" href="https://cwiki.apache.org/confluence/display/MXNET/Apache+MXNet+Home">Developer Wiki</a></li> <li><a class="main-nav-link" href="/versions/0.11.0/model_zoo/index.html">Model Zoo</a></li> <li><a class="main-nav-link" href="https://github.com/onnx/onnx-mxnet">ONNX</a></li> </li></ul> <a aria-expanded="true" aria-haspopup="true" class="main-nav-link dropdown-toggle" data-toggle="dropdown" href="#" role="button">Community </a> <ul class="dropdown-menu navbar-menu" id="package-dropdown-menu-community"> <li><a class="main-nav-link" href="http://discuss.mxnet.io">Forum</a></li> <li><a class="main-nav-link" href="https://github.com/apache/incubator-mxnet/tree/v0.11.0">Github</a></li> <li><a class="main-nav-link" href="/versions/0.11.0/community/contribute.html">Contribute</a></li> </ul> <a href="#" class="main-nav-link dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="true">0.11.0</a><ul id="package-dropdown-menu" class="dropdown-menu"><li><a href="/">master</a></li><li><a href="/versions/1.7.0/">1.7.0</a></li><li><a href=/versions/1.6.0/>1.6.0</a></li><li><a href=/versions/1.5.0/>1.5.0</a></li><li><a href=/versions/1.4.1/>1.4.1</a></li><li><a href=/versions/1.3.1/>1.3.1</a></li><li><a href=/versions/1.2.1/>1.2.1</a></li><li><a href=/versions/1.1.0/>1.1.0</a></li><li><a href=/versions/1.0.0/>1.0.0</a></li><li><a href=/versions/0.12.1/>0.12.1</a></li><li><a href=/versions/0.11.0/>0.11.0</a></li></ul></nav> <script> function getRootPath(){ return "../../" } </script> <div class="burgerIcon dropdown"> <a class="dropdown-toggle" data-toggle="dropdown" href="#" role="button">☰</a> <ul class="dropdown-menu" id="burgerMenu"> <li><a href="/versions/0.11.0/get_started/install.html">Install</a></li> <li><a class="main-nav-link" href="/versions/0.11.0/tutorials/index.html">Tutorials</a></li> <li class="dropdown-submenu dropdown"> <a aria-expanded="true" aria-haspopup="true" class="dropdown-toggle burger-link" data-toggle="dropdown" href="#" tabindex="-1">Gluon</a> <ul class="dropdown-menu navbar-menu" id="package-dropdown-menu"> <li><a class="main-nav-link" href="/versions/0.11.0/tutorials/gluon/gluon.html">About</a></li> <li><a class="main-nav-link" href="http://gluon.mxnet.io">The Straight Dope (Tutorials)</a></li> <li><a class="main-nav-link" href="https://gluon-cv.mxnet.io">GluonCV Toolkit</a></li> <li><a class="main-nav-link" href="https://gluon-nlp.mxnet.io/">GluonNLP Toolkit</a></li> </ul> </li> <li class="dropdown-submenu"> <a aria-expanded="true" aria-haspopup="true" class="dropdown-toggle burger-link" data-toggle="dropdown" href="#" tabindex="-1">API</a> <ul class="dropdown-menu"> <li><a class="main-nav-link" href="/versions/0.11.0/api/python/index.html">Python</a></li> <li><a class="main-nav-link" href="/versions/0.11.0/api/c++/index.html">C++</a></li> <li><a class="main-nav-link" href="/versions/0.11.0/api/julia/index.html">Julia</a></li> <li><a class="main-nav-link" href="/versions/0.11.0/api/perl/index.html">Perl</a></li> <li><a class="main-nav-link" href="/versions/0.11.0/api/r/index.html">R</a></li> <li><a class="main-nav-link" href="/versions/0.11.0/api/scala/index.html">Scala</a></li> </ul> </li> <li class="dropdown-submenu"> <a aria-expanded="true" aria-haspopup="true" class="dropdown-toggle burger-link" data-toggle="dropdown" href="#" tabindex="-1">Docs</a> <ul class="dropdown-menu"> <li><a href="/versions/0.11.0/how_to/faq.html" tabindex="-1">FAQ</a></li> <li><a href="/versions/0.11.0/tutorials/index.html" tabindex="-1">Tutorials</a></li> <li><a href="https://github.com/apache/incubator-mxnet/tree/v0.11.0/example" tabindex="-1">Examples</a></li> <li><a href="/versions/0.11.0/architecture/index.html" tabindex="-1">Architecture</a></li> <li><a href="https://cwiki.apache.org/confluence/display/MXNET/Apache+MXNet+Home" tabindex="-1">Developer Wiki</a></li> <li><a href="/versions/0.11.0/model_zoo/index.html" tabindex="-1">Gluon Model Zoo</a></li> <li><a href="https://github.com/onnx/onnx-mxnet" tabindex="-1">ONNX</a></li> </ul> </li> <li class="dropdown-submenu dropdown"> <a aria-haspopup="true" class="dropdown-toggle burger-link" data-toggle="dropdown" href="#" role="button" tabindex="-1">Community</a> <ul class="dropdown-menu"> <li><a href="http://discuss.mxnet.io" tabindex="-1">Forum</a></li> <li><a href="https://github.com/apache/incubator-mxnet/tree/v0.11.0" tabindex="-1">Github</a></li> <li><a href="/versions/0.11.0/community/contribute.html" tabindex="-1">Contribute</a></li> </ul> </li> <li id="dropdown-menu-position-anchor-version-mobile" class="dropdown-submenu" style="position: relative"><a href="#" tabindex="-1">0.11.0</a><ul class="dropdown-menu"><li><a tabindex="-1" href=/>master</a></li><li><a tabindex="-1" href=/versions/1.6.0/>1.6.0</a></li><li><a tabindex="-1" href=/versions/1.5.0/>1.5.0</a></li><li><a tabindex="-1" href=/versions/1.4.1/>1.4.1</a></li><li><a tabindex="-1" href=/versions/1.3.1/>1.3.1</a></li><li><a tabindex="-1" href=/versions/1.2.1/>1.2.1</a></li><li><a tabindex="-1" href=/versions/1.1.0/>1.1.0</a></li><li><a tabindex="-1" href=/versions/1.0.0/>1.0.0</a></li><li><a tabindex="-1" href=/versions/0.12.1/>0.12.1</a></li><li><a tabindex="-1" href=/versions/0.11.0/>0.11.0</a></li></ul></li></ul> </div> <div class="plusIcon dropdown"> <a class="dropdown-toggle" data-toggle="dropdown" href="#" role="button"></a> <ul class="dropdown-menu dropdown-menu-right" id="plusMenu"></ul> </div> <div id="search-input-wrap"> <form action="../../search.html" autocomplete="off" class="" method="get" role="search"> <div class="form-group inner-addon left-addon"> <input class="form-control" name="q" placeholder="Search" type="text"/> </div> <input name="check_keywords" type="hidden" value="yes"> <input name="area" type="hidden" value="default"/> </input></form> <div id="search-preview"></div> </div> <div id="searchIcon"> </div>            </div> </div> </div> <script type="text/javascript"> $('body').css('background', 'white'); </script> <div class="container"> <div class="row"> <div aria-label="main navigation" class="sphinxsidebar leftsidebar" role="navigation"> <div class="sphinxsidebarwrapper"> <ul> <li class="toctree-l1"><a class="reference internal" href="../../api/python/index.html">Python Documents</a></li> <li class="toctree-l1"><a class="reference internal" href="../../api/r/index.html">R Documents</a></li> <li class="toctree-l1"><a class="reference internal" href="../../api/julia/index.html">Julia Documents</a></li> <li class="toctree-l1"><a class="reference internal" href="../../api/c++/index.html">C++ Documents</a></li> <li class="toctree-l1"><a class="reference internal" href="../../api/scala/index.html">Scala Documents</a></li> <li class="toctree-l1"><a class="reference internal" href="../../api/perl/index.html">Perl Documents</a></li> <li class="toctree-l1"><a class="reference internal" href="../../how_to/index.html">HowTo Documents</a></li> <li class="toctree-l1"><a class="reference internal" href="../../architecture/index.html">System Documents</a></li> <li class="toctree-l1"><a class="reference internal" href="../index.html">Tutorials</a></li> </ul> </div> </div> <div class="content"> <div class="page-tracker"></div> <div class="section" id="handwritten-digit-recognition"> <h1>Handwritten Digit Recognition<a class="headerlink" href="#handwritten-digit-recognition" title="Permalink to this headline">¶</a></h1> This Scala tutorial guides you through a classic computer vision application: identifying hand written digits. Let’s train a 3-layer network (i.e multilayer perceptron network) on the MNIST dataset to classify handwritten digits. <div class="section" id="prerequisites"> <h2>Prerequisites<a class="headerlink" href="#prerequisites" title="Permalink to this headline">¶</a></h2> To complete this tutorial, we need: <ul class="simple"> <li>to compile the latest MXNet version. See the MXNet installation instructions for your operating system in <a class="reference external" href="/versions/0.11.0/get_started/install.html">Setup and Installation</a>.</li> <li>to compile the Scala API. See Scala API build instructions in <a class="reference external" href="https://github.com/dmlc/mxnet/tree/0.11.0/scala-package">Build</a>.</li> </ul> </div> <div class="section" id="define-the-network"> <h2>Define the Network<a class="headerlink" href="#define-the-network" title="Permalink to this headline">¶</a></h2> First, define the neural network’s architecture using the Symbol API: <div class="highlight-scala"><div class="highlight"><pre>import ml.dmlc.mxnet._ import ml.dmlc.mxnet.optimizer.SGD // model definition val data = Symbol.Variable("data") val fc1 = Symbol.FullyConnected(name = "fc1")()(Map("data" -> data, "num_hidden" -> 128)) val act1 = Symbol.Activation(name = "relu1")()(Map("data" -> fc1, "act_type" -> "relu")) val fc2 = Symbol.FullyConnected(name = "fc2")()(Map("data" -> act1, "num_hidden" -> 64)) val act2 = Symbol.Activation(name = "relu2")()(Map("data" -> fc2, "act_type" -> "relu")) val fc3 = Symbol.FullyConnected(name = "fc3")()(Map("data" -> act2, "num_hidden" -> 10)) val mlp = Symbol.SoftmaxOutput(name = "sm")()(Map("data" -> fc3)) </pre></div> </div> </div> <div class="section" id="load-the-data"> <h2>Load the Data<a class="headerlink" href="#load-the-data" title="Permalink to this headline">¶</a></h2> Then, load the training and validation data using DataIterators. You can download the MNIST data using the <a class="reference external" href="https://github.com/dmlc/mxnet/blob/0.11.0/scala-package/core/scripts/get_mnist_data.sh">get_mnist_data script</a>. We’ve already written a DataIterator for the MNIST dataset: <div class="highlight-scala"><div class="highlight"><pre>// load MNIST dataset val trainDataIter = IO.MNISTIter(Map( "image" -> "data/train-images-idx3-ubyte", "label" -> "data/train-labels-idx1-ubyte", "data_shape" -> "(1, 28, 28)", "label_name" -> "sm_label", "batch_size" -> "50", "shuffle" -> "1", "flat" -> "0", "silent" -> "0", "seed" -> "10")) val valDataIter = IO.MNISTIter(Map( "image" -> "data/t10k-images-idx3-ubyte", "label" -> "data/t10k-labels-idx1-ubyte", "data_shape" -> "(1, 28, 28)", "label_name" -> "sm_label", "batch_size" -> "50", "shuffle" -> "1", "flat" -> "0", "silent" -> "0")) </pre></div> </div> </div> <div class="section" id="train-the-model"> <h2>Train the model<a class="headerlink" href="#train-the-model" title="Permalink to this headline">¶</a></h2> We can use the FeedForward builder to train our network: <div class="highlight-scala"><div class="highlight"><pre>// setup model and fit the training data val model = FeedForward.newBuilder(mlp) .setContext(Context.cpu()) .setNumEpoch(10) .setOptimizer(new SGD(learningRate = 0.1f, momentum = 0.9f, wd = 0.0001f)) .setTrainData(trainDataIter) .setEvalData(valDataIter) .build() </pre></div> </div> </div> <div class="section" id="make-predictions"> <h2>Make predictions<a class="headerlink" href="#make-predictions" title="Permalink to this headline">¶</a></h2> Finally, let’s make predictions against the validation dataset and compare the predicted labels with the real labels. <div class="highlight-scala"><div class="highlight"><pre>val probArrays = model.predict(valDataIter) // in this case, we do not have multiple outputs require(probArrays.length == 1) val prob = probArrays(0) // get real labels import scala.collection.mutable.ListBuffer valDataIter.reset() val labels = ListBuffer.empty[NDArray] while (valDataIter.hasNext) { val evalData = valDataIter.next() labels += evalData.label(0).copy() } val y = NDArray.concatenate(labels) // get predicted labels val predictedY = NDArray.argmax_channel(prob) require(y.shape == predictedY.shape) // calculate accuracy var numCorrect = 0 var numTotal = 0 for ((labelElem, predElem) <- y.toArray zip predictedY.toArray) { if (labelElem == predElem) { numCorrect += 1 } numTotal += 1 } val acc = numCorrect.toFloat / numTotal println(s"Final accuracy = $acc") </pre></div> </div> Check out more MXNet Scala examples below. </div> <div class="section" id="next-steps"> <h2>Next Steps<a class="headerlink" href="#next-steps" title="Permalink to this headline">¶</a></h2> <div class="toctree-wrapper compound"> <ul> <li class="toctree-l1"><a class="reference external" href="/versions/0.11.0/api/scala/">Scala API</a></li> <li class="toctree-l1"><a class="reference external" href="https://github.com/dmlc/mxnet/tree/0.11.0/scala-package/examples/">More Scala Examples</a></li> <li class="toctree-l1"><a class="reference external" href="/versions/0.11.0/tutorials/index.html">MXNet tutorials index</a></li> </ul> </div> </div> </div> </div> </div> <div aria-label="main navigation" class="sphinxsidebar rightsidebar" role="navigation"> <div class="sphinxsidebarwrapper"> <h3><a href="../../index.html">Table Of Contents</a></h3> <ul> <li><a class="reference internal" href="#">Handwritten Digit Recognition</a><ul> <li><a class="reference internal" href="#prerequisites">Prerequisites</a></li> <li><a class="reference internal" href="#define-the-network">Define the Network</a></li> <li><a class="reference internal" href="#load-the-data">Load the Data</a></li> <li><a class="reference internal" href="#train-the-model">Train the model</a></li> <li><a class="reference internal" href="#make-predictions">Make predictions</a></li> <li><a class="reference internal" href="#next-steps">Next Steps</a></li> </ul> </li> </ul> </div> </div> </div><div class="footer"> <div class="section-disclaimer"> <div class="container"> <div> <img height="60" src="https://raw.githubusercontent.com/dmlc/web-data/master/mxnet/image/apache_incubator_logo.png"/> Apache MXNet is an effort undergoing incubation at The Apache Software Foundation (ASF), sponsored by the Apache Incubator. Incubation is required of all newly accepted projects until a further review indicates that the infrastructure, communications, and decision making process have stabilized in a manner consistent with other successful ASF projects. While incubation status is not necessarily a reflection of the completeness or stability of the code, it does indicate that the project has yet to be fully endorsed by the ASF. "Copyright © 2017-2018, The Apache Software Foundation Apache MXNet, MXNet, Apache, the Apache feather, and the Apache MXNet project logo are either registered trademarks or trademarks of the Apache Software Foundation." </div> </div> </div> </div>  </div> <script crossorigin="anonymous" integrity="sha384-0mSbJDEHialfmuBBQP6A4Qrprq5OVfW37PRR3j5ELqxss1yVqOtnepnHVP9aJ7xS" src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js"></script> <script src="../../_static/js/sidebar.js" type="text/javascript"></script> <script src="../../_static/js/search.js" type="text/javascript"></script> <script src="../../_static/js/navbar.js" type="text/javascript"></script> <script src="../../_static/js/clipboard.min.js" type="text/javascript"></script> <script src="../../_static/js/copycode.js" type="text/javascript"></script> <script src="../../_static/js/page.js" type="text/javascript"></script> <script src="../../_static/js/docversion.js" type="text/javascript"></script> <script type="text/javascript"> $('body').ready(function () { $('body').css('visibility', 'visible'); }); </script> </body> </html>

versions/0.11.0/tutorials/scala/mnist.html (341 lines of code) (raw):