home | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (MnistManager.java)

This example Java source code file (MnistManager.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

bufferedwriter, filewriter, header_size, illegalstateexception, images, ioexception, mnistimagefile, mnistlabelfile, mnistmanager, p3\n, string, stringbuilder, util

The MnistManager.java Java example source code

/*
 *
 *  * Copyright 2015 Skymind,Inc.
 *  *
 *  *    Licensed under the Apache License, Version 2.0 (the "License");
 *  *    you may not use this file except in compliance with the License.
 *  *    You may obtain a copy of the License at
 *  *
 *  *        http://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.
 *
 */

package org.deeplearning4j.datasets.mnist;


import org.deeplearning4j.datasets.fetchers.MnistDataFetcher;

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Arrays;


/**
 * <p>
 * Utility class for working with the MNIST database.
 * <p>
 * Provides methods for traversing the images and labels data files separately,
 * as well as simultaneously.
 * <p>
 * Provides also method for exporting an image by writing it as a PPM file.
 * <p> 
 * Example usage:
 * <pre>
 *  MnistManager m = new MnistManager("t10k-images.idx3-ubyte", "t10k-labels.idx1-ubyte");
 *  m.setCurrent(10); //index of the image that we are interested in
 *  int[][] image = m.readImage();
 *  System.out.println("Label:" + m.readLabel());
 *  MnistManager.writeImageToPpm(image, "10.ppm");
 * </pre>
 */
public class MnistManager {
    MnistImageFile images;
    private MnistLabelFile labels;

    private byte[][] imagesArr;
    private int[] labelsArr;
    private static final int HEADER_SIZE = 8;

    /**
     * Writes the given image in the given file using the PPM data format.
     *
     * @param image
     * @param ppmFileName
     * @throws IOException
     */
    public static void writeImageToPpm(int[][] image, String ppmFileName) throws IOException {
        try (BufferedWriter ppmOut = new BufferedWriter(new FileWriter(ppmFileName))) {
            int rows = image.length;
            int cols = image[0].length;
            ppmOut.write("P3\n");
            ppmOut.write("" + rows + " " + cols + " 255\n");
            for (int i = 0; i < rows; i++) {
                StringBuilder s = new StringBuilder();
                for (int j = 0; j < cols; j++) {
                    s.append(image[i][j] + " " + image[i][j] + " " + image[i][j] + "  ");
                }
                ppmOut.write(s.toString());
            }
        }

    }

    /**
     * Constructs an instance managing the two given data files. Supports
     * <code>NULL value for one of the arguments in case reading only one
     * of the files (images and labels) is required.
     *
     * @param imagesFile
     *            Can be <code>NULL. In that case all future operations
     *            using that file will fail.
     * @param labelsFile
     *            Can be <code>NULL. In that case all future operations
     *            using that file will fail.
     * @throws IOException
     */
    public MnistManager(String imagesFile, String labelsFile, boolean train) throws IOException {
        if (imagesFile != null) {
            images = new MnistImageFile(imagesFile, "r");
            if(train) imagesArr = new MnistImageFile(imagesFile, "r").readImagesUnsafe(MnistDataFetcher.NUM_EXAMPLES);
            else imagesArr = images.readImagesUnsafe(MnistDataFetcher.NUM_EXAMPLES_TEST);
        }
        if (labelsFile != null) {
            labels = new MnistLabelFile(labelsFile, "r");
            if(train) labelsArr = labels.readLabels(MnistDataFetcher.NUM_EXAMPLES);
            else labelsArr = labels.readLabels(MnistDataFetcher.NUM_EXAMPLES_TEST);
        }
        System.out.println();
    }

    public MnistManager(String imagesFile, String labelsFile) throws IOException{
        this(imagesFile,labelsFile,true);
    }

    /**
     * Reads the current image.
     *
     * @return matrix
     * @throws IOException
     */
    public int[][] readImage() throws IOException {
        if (images == null) {
            throw new IllegalStateException("Images file not initialized.");
        }
        return images.readImage();
    }

    public byte[] readImageUnsafe(int i){
        return imagesArr[i];
    }

    /**
     * Set the position to be read.
     *
     * @param index
     */
    public void setCurrent(int index) {
        images.setCurrentIndex(index);
        labels.setCurrentIndex(index);
    }

    /**
     * Reads the current label.
     *
     * @return int
     * @throws IOException
     */
    public int readLabel() throws IOException {
        if (labels == null) {
            throw new IllegalStateException("labels file not initialized.");
        }
        return labels.readLabel();
    }

    public int readLabel(int i){
        return labelsArr[i];
    }

    /**
     * Get the underlying images file as {@link MnistImageFile}.
     *
     * @return {@link MnistImageFile}.
     */
    public MnistImageFile getImages() {
        return images;
    }

    /**
     * Get the underlying labels file as {@link MnistLabelFile}.
     *
     * @return {@link MnistLabelFile}.
     */
    public MnistLabelFile getLabels() {
        return labels;
    }

    /**
     * Close any resources opened by the manager.
     */
    public void close() {
        if(images != null) {
            try {
                images.close();
            } catch (IOException e) {}
            images = null;
        }
        if(labels != null) {
            try {
                labels.close();
            } catch (IOException e) {}
            labels = null;
        }
    }
}

Other Java examples (source code examples)

Here is a short list of links related to this Java MnistManager.java source code file:



my book on functional programming

 

new blog posts

 

Copyright 1998-2019 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.