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• JSONSaver.java

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weka.core.converters.JSONSaver Maven / Gradle / Ivy

/*
 *   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 .
 */

/*
 * 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;

/**
 *  Writes to a destination that is in JSON format.

 * The data can be compressed with gzip, in order to save space.

 * 

 * For more information, see JSON homepage:

 * http://www.json.org/
 * 

 * 
 * 
 *  Valid options are:
 * 

 * 
 * 
 * -i <the input file>
 *  The input file
 * 
 * 
 * 
 * -o <the output file>
 *  The output file
 * 
 * 
 * 
 * -C <class index>
 *  The class index (first and last are valid as well).
 *  (default: last)
 * 
 * 
 * 
 * -compress
 *  Compresses the data (uses '.json.gz' as extension instead of '.json')
 *  (default: off)
 * 
 * 
 * 
 * 
 * @author FracPete (fracpete at waikato dot ac dot nz)
 * @version $Revision: 14861 $
 * @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 listOptions() {
    Vector result = new Vector();

    result.addElement(new Option(
      "\tThe class index (first and last are valid as well).\n"
        + "\t(default: last)", "C", 1, "-C "));

    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 result = new Vector();

    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.
   * 

   * 
   *  Valid options are:
   * 

   * 
   * 
   * -i <the input file>
   *  The input file
   * 
   * 
   * 
   * -o <the output file>
   *  The output file
   * 
   * 
   * 
   * -C <class index>
   *  The class index (first and last are valid as well).
   *  (default: last)
   * 
   * 
   * 
   * -compress
   *  Compresses the data (uses '.json.gz' as extension instead of '.json')
   *  (default: off)
   * 
   * 
   * 
   * 
   * @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: 14861 $");
  }

  /**
   * Main method.
   * 
   * @param args should contain the options of a Saver.
   */
  public static void main(String[] args) {
    runFileSaver(new JSONSaver(), args);
  }
}