Add a code on logistic regression article (BAEL-3081)

ml/README.md

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+### Sample deeplearning4j Project
+This is a sample project for the [deeplearning4j](https://deeplearning4j.org) library.
+
+### Relevant Articles:
+- [A Guide to Deeplearning4j](http://www.baeldung.com/deeplearning4j)

ml/pom.xml

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+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung.deeplearning4j</groupId>
+    <artifactId>ml</artifactId>
+    <version>1.0-SNAPSHOT</version>
+    <name>Machine Learning</name>
+    <packaging>jar</packaging>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.nd4j</groupId>
+            <artifactId>nd4j-native-platform</artifactId>
+            <version>${dl4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.deeplearning4j</groupId>
+            <artifactId>deeplearning4j-core</artifactId>
+            <version>${dl4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.deeplearning4j</groupId>
+            <artifactId>deeplearning4j-nn</artifactId>
+            <version>${dl4j.version}</version>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/org.datavec/datavec-api -->
+        <dependency>
+            <groupId>org.datavec</groupId>
+            <artifactId>datavec-api</artifactId>
+            <version>${dl4j.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.httpcomponents</groupId>
+            <artifactId>httpclient</artifactId>
+            <version>4.3.5</version>
+        </dependency>
+
+
+    </dependencies>
+
+    <properties>
+        <dl4j.version>1.0.0-beta4</dl4j.version>
+    </properties>
+
+</project>

ml/src/main/java/com/baeldung/logreg/DataUtilities.java

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+/*******************************************************************************
+ * Copyright (c) 2015-2019 Skymind, Inc.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License, Version 2.0 which is available at
+ * https://www.apache.org/licenses/LICENSE-2.0.
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ******************************************************************************/
+
+package com.baeldung.logreg;
+
+import org.apache.commons.compress.archivers.tar.TarArchiveEntry;
+import org.apache.commons.compress.archivers.tar.TarArchiveInputStream;
+import org.apache.commons.compress.compressors.gzip.GzipCompressorInputStream;
+import org.apache.http.HttpEntity;
+import org.apache.http.client.methods.CloseableHttpResponse;
+import org.apache.http.client.methods.HttpGet;
+import org.apache.http.impl.client.CloseableHttpClient;
+import org.apache.http.impl.client.HttpClientBuilder;
+
+import java.io.*;
+
+/**
+ * Common data utility functions.
+ * 
+ * @author fvaleri
+ */
+public class DataUtilities {
+
+  /**
+   * Download a remote file if it doesn't exist.
+   * @param remoteUrl URL of the remote file.
+   * @param localPath Where to download the file.
+   * @return True if and only if the file has been downloaded.
+   * @throws Exception IO error.
+   */
+  public static boolean downloadFile(String remoteUrl, String localPath) throws IOException {
+    boolean downloaded = false;
+    if (remoteUrl == null || localPath == null)
+      return downloaded;
+    File file = new File(localPath);
+    if (!file.exists()) {
+      file.getParentFile().mkdirs();
+      HttpClientBuilder builder = HttpClientBuilder.create();
+      CloseableHttpClient client = builder.build();
+      try (CloseableHttpResponse response = client.execute(new HttpGet(remoteUrl))) {
+        HttpEntity entity = response.getEntity();
+        if (entity != null) {
+          try (FileOutputStream outstream = new FileOutputStream(file)) {
+            entity.writeTo(outstream);
+            outstream.flush();
+            outstream.close();
+          }
+        }
+      }
+      downloaded = true;
+    }
+    if (!file.exists())
+      throw new IOException("File doesn't exist: " + localPath);
+    return downloaded;
+  }
+
+  /**
+   * Extract a "tar.gz" file into a local folder.
+   * @param inputPath Input file path.
+   * @param outputPath Output directory path.
+   * @throws IOException IO error.
+   */
+  public static void extractTarGz(String inputPath, String outputPath) throws IOException {
+    if (inputPath == null || outputPath == null)
+      return;
+    final int bufferSize = 4096;
+    if (!outputPath.endsWith("" + File.separatorChar))
+      outputPath = outputPath + File.separatorChar;
+    try (TarArchiveInputStream tais = new TarArchiveInputStream(
+        new GzipCompressorInputStream(new BufferedInputStream(new FileInputStream(inputPath))))) {
+      TarArchiveEntry entry;
+      while ((entry = (TarArchiveEntry) tais.getNextEntry()) != null) {
+        if (entry.isDirectory()) {
+          new File(outputPath + entry.getName()).mkdirs();
+        } else {
+          int count;
+          byte data[] = new byte[bufferSize];
+          FileOutputStream fos = new FileOutputStream(outputPath + entry.getName());
+          BufferedOutputStream dest = new BufferedOutputStream(fos, bufferSize);
+          while ((count = tais.read(data, 0, bufferSize)) != -1) {
+            dest.write(data, 0, count);
+          }
+          dest.close();
+        }
+      }
+    }
+  }
+
+}

ml/src/main/java/com/baeldung/logreg/MnistClassifier.java

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+package com.baeldung.logreg;
+
+import java.io.File;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Random;
+
+import org.datavec.api.io.labels.ParentPathLabelGenerator;
+import org.datavec.api.split.FileSplit;
+import org.datavec.image.loader.NativeImageLoader;
+import org.datavec.image.recordreader.ImageRecordReader;
+import org.deeplearning4j.datasets.datavec.RecordReaderDataSetIterator;
+import org.deeplearning4j.nn.conf.MultiLayerConfiguration;
+import org.deeplearning4j.nn.conf.NeuralNetConfiguration;
+import org.deeplearning4j.nn.conf.inputs.InputType;
+import org.deeplearning4j.nn.conf.layers.ConvolutionLayer;
+import org.deeplearning4j.nn.conf.layers.DenseLayer;
+import org.deeplearning4j.nn.conf.layers.OutputLayer;
+import org.deeplearning4j.nn.conf.layers.SubsamplingLayer;
+import org.deeplearning4j.nn.multilayer.MultiLayerNetwork;
+import org.deeplearning4j.nn.weights.WeightInit;
+import org.deeplearning4j.optimize.listeners.ScoreIterationListener;
+import org.deeplearning4j.util.ModelSerializer;
+import org.nd4j.evaluation.classification.Evaluation;
+import org.nd4j.linalg.activations.Activation;
+import org.nd4j.linalg.dataset.api.iterator.DataSetIterator;
+import org.nd4j.linalg.dataset.api.preprocessor.DataNormalization;
+import org.nd4j.linalg.dataset.api.preprocessor.ImagePreProcessingScaler;
+import org.nd4j.linalg.learning.config.Nesterovs;
+import org.nd4j.linalg.lossfunctions.LossFunctions;
+import org.nd4j.linalg.schedule.MapSchedule;
+import org.nd4j.linalg.schedule.ScheduleType;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Handwritten digit image classification based on LeNet-5 architecture by Yann LeCun.
+ * 
+ * This code accompanies the article "Logistic  regression in Java" and is heavily based on 
+ * <a href="https://github.com/deeplearning4j/dl4j-examples/blob/master/dl4j-examples/src/main/java/org/deeplearning4j/examples/convolution/mnist/MnistClassifier.java">MnistClassifier</a>. 
+ * Some minor changes have been made in order to make article's flow smoother.
+ * 
+ */
+
+public class MnistClassifier {
+    private static final Logger logger = LoggerFactory.getLogger(MnistClassifier.class);
+    private static final String basePath = System.getProperty("java.io.tmpdir") + "mnist" + File.separator;
+    private static final File modelPath = new File(basePath + "mnist-model.zip");
+    private static final String dataUrl = "http://github.com/myleott/mnist_png/raw/master/mnist_png.tar.gz";
+
+    public static void main(String[] args) throws Exception {
+        // input image sizes in pixels
+        int height = 28;
+        int width = 28;
+        // input image colour depth (1 for gray scale images)
+        int channels = 1;
+        // the number of output classes
+        int outputClasses = 10;
+        // number of samples that will be propagated through the network in each iteration
+        int batchSize = 54;
+        // total number of training epochs
+        int epochs = 1;
+
+        // initialize a pseudorandom number generator
+        int seed = 1234;
+        Random randNumGen = new Random(seed);
+
+        final String path = basePath + "mnist_png" + File.separator;
+        if (!new File(path).exists()) {
+            logger.debug("Downloading data {}", dataUrl);
+            String localFilePath = basePath + "mnist_png.tar.gz";
+            logger.info("local file: {}", localFilePath);
+            if (DataUtilities.downloadFile(dataUrl, localFilePath)) {
+                DataUtilities.extractTarGz(localFilePath, basePath);
+            }
+        } else {
+            logger.info("local file exists {}", path);
+
+        }
+
+        logger.info("Vectorizing data...");
+        // vectorization of train data
+        File trainData = new File(path + "training");
+        FileSplit trainSplit = new FileSplit(trainData, NativeImageLoader.ALLOWED_FORMATS, randNumGen);
+        // use parent directory name as the image label
+        ParentPathLabelGenerator labelMaker = new ParentPathLabelGenerator();
+        ImageRecordReader trainRR = new ImageRecordReader(height, width, channels, labelMaker);
+        trainRR.initialize(trainSplit);
+        DataSetIterator train = new RecordReaderDataSetIterator(trainRR, batchSize, 1, outputClasses);
+
+        // pixel values from 0-255 to 0-1 (min-max scaling)
+        DataNormalization imageScaler = new ImagePreProcessingScaler();
+        imageScaler.fit(train);
+        train.setPreProcessor(imageScaler);
+
+        // vectorization of test data
+        File testData = new File(path + "testing");
+        FileSplit testSplit = new FileSplit(testData, NativeImageLoader.ALLOWED_FORMATS, randNumGen);
+        ImageRecordReader testRR = new ImageRecordReader(height, width, channels, labelMaker);
+        testRR.initialize(testSplit);
+        DataSetIterator test = new RecordReaderDataSetIterator(testRR, batchSize, 1, outputClasses);
+        // same normalization for better results
+        test.setPreProcessor(imageScaler);
+
+        logger.info("Network configuration and training...");
+        // reduce the learning rate as the number of training epochs increases
+        // iteration #, learning rate
+        Map<Integer, Double> learningRateSchedule = new HashMap<>();
+        learningRateSchedule.put(0, 0.06);
+        learningRateSchedule.put(200, 0.05);
+        learningRateSchedule.put(600, 0.028);
+        learningRateSchedule.put(800, 0.0060);
+        learningRateSchedule.put(1000, 0.001);
+
+        final ConvolutionLayer layer1 = new ConvolutionLayer.Builder(5, 5).nIn(channels)
+            .stride(1, 1)
+            .nOut(20)
+            .activation(Activation.IDENTITY)
+            .build();
+        final SubsamplingLayer layer2 = new SubsamplingLayer.Builder(SubsamplingLayer.PoolingType.MAX).kernelSize(2, 2)
+            .stride(2, 2)
+            .build();
+        // nIn need not specified in later layers
+        final ConvolutionLayer layer3 = new ConvolutionLayer.Builder(5, 5).stride(1, 1)
+            .nOut(50)
+            .activation(Activation.IDENTITY)
+            .build();
+        final DenseLayer layer4 = new DenseLayer.Builder().activation(Activation.RELU)
+            .nOut(500)
+            .build();
+        final OutputLayer layer5 = new OutputLayer.Builder(LossFunctions.LossFunction.NEGATIVELOGLIKELIHOOD).nOut(outputClasses)
+            .activation(Activation.SOFTMAX)
+            .build();
+        final MultiLayerConfiguration config = new NeuralNetConfiguration.Builder().seed(seed)
+            .l2(0.0005) // ridge regression value
+            .updater(new Nesterovs(new MapSchedule(ScheduleType.ITERATION, learningRateSchedule)))
+            .weightInit(WeightInit.XAVIER)
+            .list()
+            .layer(layer1)
+            .layer(layer2)
+            .layer(layer3)
+            .layer(layer2)
+            .layer(layer4)
+            .layer(layer5)
+            .setInputType(InputType.convolutionalFlat(height, width, channels))
+            .build();
+
+        final MultiLayerNetwork model = new MultiLayerNetwork(config);
+        model.init();
+        model.setListeners(new ScoreIterationListener(100));
+        logger.info("Total num of params: {}", model.numParams());
+
+        // evaluation while training (the score should go down)
+        for (int i = 0; i < epochs; i++) {
+            model.fit(train);
+            logger.info("Completed epoch {}", i);
+            train.reset();
+            test.reset();
+        }
+        Evaluation eval = model.evaluate(test);
+        logger.info(eval.stats());
+
+        ModelSerializer.writeModel(model, modelPath, true);
+        logger.info("The MINIST model has been saved in {}", modelPath.getPath());
+    }
+}

ml/src/main/java/com/baeldung/logreg/MnistPrediction.java

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+package com.baeldung.logreg;
+
+import java.io.File;
+import java.io.IOException;
+
+import javax.swing.JFileChooser;
+
+import org.datavec.image.loader.NativeImageLoader;
+import org.deeplearning4j.nn.multilayer.MultiLayerNetwork;
+import org.deeplearning4j.util.ModelSerializer;
+import org.nd4j.linalg.api.ndarray.INDArray;
+import org.nd4j.linalg.dataset.api.preprocessor.ImagePreProcessingScaler;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class MnistPrediction {
+    private static final Logger logger = LoggerFactory.getLogger(MnistPrediction.class);
+    private static final File modelPath = new File(System.getProperty("java.io.tmpdir") + "mnist" + File.separator + "mnist-model.zip");
+    private static final int height = 28;
+    private static final int width = 28;
+    private static final int channels = 1;
+
+    /**
+     * Opens a popup that allows to select a file from the filesystem.
+     * @return
+     */
+    public static String fileChose() {
+        JFileChooser fc = new JFileChooser();
+        int ret = fc.showOpenDialog(null);
+        if (ret == JFileChooser.APPROVE_OPTION) {
+            File file = fc.getSelectedFile();
+            return file.getAbsolutePath();
+        } else {
+            return null;
+        }
+    }
+
+    public static void main(String[] args) throws IOException {
+        String path = fileChose().toString();
+        MultiLayerNetwork model = ModelSerializer.restoreMultiLayerNetwork(modelPath);
+        File file = new File(path);
+
+        INDArray image = new NativeImageLoader(height, width, channels).asMatrix(file);
+        new ImagePreProcessingScaler(0, 1).transform(image);
+        
+        // Pass through to neural Net
+        INDArray output = model.output(image);
+
+        logger.info("File: {}", path);
+        logger.info(output.toString());
+    }
+
+}

ml/src/main/resources/logback.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">
+        <encoder>
+            <pattern>%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n
+            </pattern>
+        </encoder>
+    </appender>
+
+    <root level="INFO">
+        <appender-ref ref="STDOUT" />
+    </root>
+</configuration>

pom.xml

@@ -524,6 +524,7 @@
 				<module>metrics</module>
 				<!-- <module>micronaut</module> --> <!-- Fixing in BAEL-10877 -->
 				<module>microprofile</module>
+                <module>ml</module>
 				<module>msf4j</module>
 				<!-- <module>muleesb</module> --> <!-- Fixing in BAEL-10878 -->
 				<module>mustache</module>
@@ -1216,6 +1217,7 @@
 				<module>metrics</module>
 				<!-- <module>micronaut</module> --> <!-- Fixing in BAEL-10877 -->
 				<module>microprofile</module>
+                <module>ml</module>
 				<module>msf4j</module>
 				<!-- <module>muleesb</module> --> <!-- Fixing in BAEL-10878 -->
 				<module>mustache</module>