Java tutorial
/* * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ /* * JSONSaver.java * Copyright (C) 2009-2012 University of Waikato, Hamilton, New Zealand * */ package weka.core.converters; import java.io.File; import java.io.IOException; import java.io.OutputStream; import java.io.PrintWriter; import java.util.Collections; import java.util.Enumeration; import java.util.Vector; import java.util.zip.GZIPOutputStream; import weka.core.*; import weka.core.Capabilities.Capability; import weka.core.json.JSONInstances; import weka.core.json.JSONNode; /** * <!-- globalinfo-start --> Writes to a destination that is in JSON format.<br/> * The data can be compressed with gzip, in order to save space.<br/> * <br/> * For more information, see JSON homepage:<br/> * http://www.json.org/ * <p/> * <!-- globalinfo-end --> * * <!-- options-start --> Valid options are: * <p/> * * <pre> * -i <the input file> * The input file * </pre> * * <pre> * -o <the output file> * The output file * </pre> * * <pre> * -C <class index> * The class index (first and last are valid as well). * (default: last) * </pre> * * <pre> * -compress * Compresses the data (uses '.json.gz' as extension instead of '.json') * (default: off) * </pre> * * <!-- options-end --> * * @author FracPete (fracpete at waikato dot ac dot nz) * @version $Revision$ * @see Saver */ public class JSONSaver extends AbstractFileSaver implements BatchConverter, WeightedInstancesHandler { /** for serialization. */ private static final long serialVersionUID = -1047134047244534557L; /** the class index. */ protected SingleIndex m_ClassIndex = new SingleIndex(); /** whether to compress the output. */ protected boolean m_CompressOutput = false; /** * Constructor. */ public JSONSaver() { resetOptions(); } /** * Returns a string describing this Saver. * * @return a description of the Saver suitable for displaying in the * explorer/experimenter gui */ public String globalInfo() { return "Writes to a destination that is in JSON format.\n" + "The data can be compressed with gzip, in order to save space.\n\n" + "For more information, see JSON homepage:\n" + "http://www.json.org/"; } /** * Returns an enumeration describing the available options. * * @return an enumeration of all the available options. */ @Override public Enumeration<Option> listOptions() { Vector<Option> result = new Vector<Option>(); result.addElement( new Option("\tThe class index (first and last are valid as well).\n" + "\t(default: last)", "C", 1, "-C <class index>")); result.addElement(new Option( "\tCompresses the data (uses '" + JSONLoader.FILE_EXTENSION_COMPRESSED + "' as extension instead of '" + JSONLoader.FILE_EXTENSION + "')\n" + "\t(default: off)", "compress", 0, "-compress")); result.addAll(Collections.list(super.listOptions())); return result.elements(); } /** * returns the options of the current setup. * * @return the current options */ @Override public String[] getOptions() { Vector<String> result = new Vector<String>(); if (getClassIndex().length() != 0) { result.add("-C"); result.add(getClassIndex()); } if (getCompressOutput()) { result.add("-compress"); } Collections.addAll(result, super.getOptions()); return result.toArray(new String[result.size()]); } /** * Parses the options for this object. * <p/> * * <!-- options-start --> Valid options are: * <p/> * * <pre> * -i <the input file> * The input file * </pre> * * <pre> * -o <the output file> * The output file * </pre> * * <pre> * -C <class index> * The class index (first and last are valid as well). * (default: last) * </pre> * * <pre> * -compress * Compresses the data (uses '.json.gz' as extension instead of '.json') * (default: off) * </pre> * * <!-- options-end --> * * @param options the options to use * @throws Exception if setting of options fails */ @Override public void setOptions(String[] options) throws Exception { String tmpStr; tmpStr = Utils.getOption('C', options); if (tmpStr.length() != 0) { setClassIndex(tmpStr); } else { setClassIndex("last"); } setCompressOutput(Utils.getFlag("compress", options)); super.setOptions(options); Utils.checkForRemainingOptions(options); } /** * Returns a description of the file type. * * @return a short file description */ @Override public String getFileDescription() { return "JSON data files"; } /** * Gets all the file extensions used for this type of file. * * @return the file extensions */ @Override public String[] getFileExtensions() { return new String[] { JSONLoader.FILE_EXTENSION, JSONLoader.FILE_EXTENSION_COMPRESSED }; } /** * Sets the destination file. * * @param outputFile the destination file. * @throws IOException throws an IOException if file cannot be set */ @Override public void setFile(File outputFile) throws IOException { if (outputFile.getAbsolutePath().endsWith(JSONLoader.FILE_EXTENSION_COMPRESSED)) { setCompressOutput(true); } super.setFile(outputFile); } /** * Resets the Saver. */ @Override public void resetOptions() { super.resetOptions(); if (getCompressOutput()) { setFileExtension(JSONLoader.FILE_EXTENSION_COMPRESSED); } else { setFileExtension(JSONLoader.FILE_EXTENSION); } } /** * Returns the tip text for this property. * * @return tip text for this property suitable for displaying in the * explorer/experimenter gui */ public String classIndexTipText() { return "Sets the class index (\"first\" and \"last\" are valid values)"; } /** * Get the index of the class attribute. * * @return the index of the class attribute */ public String getClassIndex() { return m_ClassIndex.getSingleIndex(); } /** * Sets index of the class attribute. * * @param value the index of the class attribute */ public void setClassIndex(String value) { m_ClassIndex.setSingleIndex(value); } /** * Returns the tip text for this property. * * @return tip text for this property suitable for displaying in the * explorer/experimenter gui */ public String compressOutputTipText() { return "Optional compression of the output data"; } /** * Gets whether the output data is compressed. * * @return true if the output data is compressed */ public boolean getCompressOutput() { return m_CompressOutput; } /** * Sets whether to compress the output. * * @param value if truee the output will be compressed */ public void setCompressOutput(boolean value) { m_CompressOutput = value; } /** * Returns the Capabilities of this saver. * * @return the capabilities of this object * @see Capabilities */ @Override public Capabilities getCapabilities() { Capabilities result = super.getCapabilities(); // attributes result.enable(Capability.NOMINAL_ATTRIBUTES); result.enable(Capability.NUMERIC_ATTRIBUTES); result.enable(Capability.DATE_ATTRIBUTES); result.enable(Capability.STRING_ATTRIBUTES); result.enable(Capability.MISSING_VALUES); // class result.enable(Capability.NOMINAL_CLASS); result.enable(Capability.NUMERIC_CLASS); result.enable(Capability.DATE_CLASS); result.enable(Capability.STRING_CLASS); result.enable(Capability.MISSING_CLASS_VALUES); result.enable(Capability.NO_CLASS); return result; } /** * Sets instances that should be stored. * * @param instances the instances */ @Override public void setInstances(Instances instances) { if (m_ClassIndex.getSingleIndex().length() != 0) { m_ClassIndex.setUpper(instances.numAttributes() - 1); instances.setClassIndex(m_ClassIndex.getIndex()); } super.setInstances(instances); } /** * Sets the destination output stream. * * @param output the output stream. * @throws IOException throws an IOException if destination cannot be set */ @Override public void setDestination(OutputStream output) throws IOException { if (getCompressOutput()) { super.setDestination(new GZIPOutputStream(output)); } else { super.setDestination(output); } } /** * Writes a Batch of instances. * * @throws IOException throws IOException if saving in batch mode is not * possible */ @Override public void writeBatch() throws IOException { if (getInstances() == null) { throw new IOException("No instances to save"); } if (getRetrieval() == INCREMENTAL) { throw new IOException("Batch and incremental saving cannot be mixed."); } setRetrieval(BATCH); setWriteMode(WRITE); PrintWriter outW; if ((retrieveFile() == null) && (getWriter() == null)) { outW = new PrintWriter(System.out); } else { outW = new PrintWriter(getWriter()); } JSONNode json = JSONInstances.toJSON(getInstances()); StringBuffer buffer = new StringBuffer(); json.toString(buffer); outW.println(buffer.toString()); outW.flush(); if (getWriter() != null) { outW.close(); } setWriteMode(WAIT); outW = null; resetWriter(); setWriteMode(CANCEL); } /** * Returns the revision string. * * @return the revision */ @Override public String getRevision() { return RevisionUtils.extract("$Revision$"); } /** * Main method. * * @param args should contain the options of a Saver. */ public static void main(String[] args) { runFileSaver(new JSONSaver(), args); } }