/*
* 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 2 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, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
* JSONInstances.java
* Copyright (C) 2009 University of Waikato, Hamilton, New Zealand
*/
package weka.core.json;
import weka.core.Attribute;
import weka.core.Instance;
import weka.core.Instances;
import weka.core.DenseInstance;
import weka.core.SparseInstance;
import weka.core.Utils;
import weka.core.converters.ConverterUtils.DataSource;
import java.util.ArrayList;
/**
* Class for transforming Instances objects into <a href="http://www.json.org/" target="_blank">JSON</a>
* objects and vice versa.
*
* @author FracPete (fracpete at waikato dot ac dot nz)
* @version $Revision: 5987 $
*/
public class JSONInstances {
/** the header section. */
public final static String HEADER = "header";
/** the data section. */
public final static String DATA = "data";
/** the relation name. */
public final static String RELATION = "relation";
/** the attributes object. */
public final static String ATTRIBUTES = "attributes";
/** the name attribute. */
public final static String NAME = "name";
/** the type attribute. */
public final static String TYPE = "type";
/** the class attribute indicator. */
public final static String CLASS = "class";
/** the labels attribute. */
public final static String LABELS = "labels";
/** the weight attribute. */
public final static String WEIGHT = "weight";
/** the dateformat attribute. */
public final static String DATEFORMAT = "dateformat";
/** the sparse attribute. */
public final static String SPARSE = "sparse";
/** the values attribute. */
public final static String VALUES = "values";
/** the separator for index/value in case of sparse instances. */
public final static String SPARSE_SEPARATOR = ":";
/**
* Turns the JSON object into an Attribute, if possible.
*
* @param att the JSON object to turn into an Attribute
* @param classAtt for storing whether the attribute is the class attribute
* @return the Attribute, null in case of an error
*/
protected static Attribute toAttribute(JSONNode att, boolean[] classAtt) {
Attribute result;
String name;
String type;
String dateformat;
JSONNode labels;
ArrayList<String> values;
int i;
double weight;
name = (String) att.getChild(NAME).getValue("noname");
type = (String) att.getChild(TYPE).getValue("");
weight = (Double) att.getChild(WEIGHT).getValue(new Double(1.0));
if (type.equals(Attribute.typeToString(Attribute.NUMERIC))) {
result = new Attribute(name);
}
else if (type.equals(Attribute.typeToString(Attribute.NOMINAL))) {
labels = att.getChild(LABELS);
values = new ArrayList<String>();
for (i = 0; i < labels.getChildCount(); i++)
values.add((String)((JSONNode) labels.getChildAt(i)).getValue());
result = new Attribute(name, values);
}
else if (type.equals(Attribute.typeToString(Attribute.DATE))) {
dateformat = (String) att.getChild(TYPE).getValue("yyyy-MM-dd'T'HH:mm:ss");
result = new Attribute(name, dateformat);
}
else if (type.equals(Attribute.typeToString(Attribute.STRING))) {
result = new Attribute(name, (ArrayList<String>) null);
}
else {
System.err.println("Unhandled attribute type '" + type + "'!");
return null;
}
result.setWeight(weight);
return result;
}
/**
* Turns the JSON Object into an Instance, if possible.
*
* @param inst the JSON object to turn into an Instance
* @param data the data so far (only used for header information)
* @return the Instance, null in case of an error
*/
protected static Instance toInstance(JSONNode inst, Instances data) {
Instance result;
boolean sparse;
double weight;
JSONNode values;
int i;
int index;
int pos;
String value;
double[] vals;
sparse = (Boolean) inst.getChild(SPARSE).getValue(new Boolean(false));
weight = (Double) inst.getChild(WEIGHT).getValue(new Double(1.0));
values = inst.getChild(VALUES);
vals = new double[data.numAttributes()];
for (i = 0; i < values.getChildCount(); i++) {
if (sparse) {
value = "" + ((JSONNode) values.getChildAt(i)).getValue();
pos = value.indexOf(SPARSE_SEPARATOR);
index = Integer.parseInt(value.substring(0, pos));
value = value.substring(pos + 1);
}
else {
index = i;
value = "" + ((JSONNode) values.getChildAt(i)).getValue();
}
try {
if (data.attribute(index).isNumeric()) {
vals[index] = Double.parseDouble(value);
}
else if (data.attribute(index).isNominal()) {
vals[index] = data.attribute(index).indexOfValue(value);
if ((vals[index] == -1) && value.startsWith("'") && value.endsWith("'"))
vals[index] = data.attribute(index).indexOfValue(Utils.unquote(value));
if (vals[index] == -1) {
System.err.println("Unknown label '" + value + "' for attribute #" + (index+1) + "!");
return null;
}
}
else if (data.attribute(index).isDate()) {
vals[index] = data.attribute(index).parseDate(value);
}
else if (data.attribute(index).isString()) {
vals[index] = data.attribute(index).addStringValue(value);
}
else {
System.err.println("Unhandled attribute type '" + Attribute.typeToString(data.attribute(index).type()) + "'!");
return null;
}
}
catch (Exception e) {
System.err.println("Error parsing value #" + (index+1) + ": " + e.toString());
return null;
}
}
result = new DenseInstance(weight, vals);
result.setDataset(data);
return result;
}
/**
* Turns a JSON object, if possible, into an Instances object.
*
* @param json the JSON object to convert
* @param onlyHeader whether to retrieve only the header
* @return the generated Instances object, null if not possible
*/
protected static Instances toInstances(JSONNode json, boolean onlyHeader) {
Instances result;
JSONNode header;
JSONNode attributes;
JSONNode data;
ArrayList<Attribute> atts;
Attribute att;
Instance inst;
int i;
int classIndex;
boolean[] classAtt;
header = json.getChild(HEADER);
if (header == null) {
System.err.println("No '" + HEADER + "' section!");
return null;
}
data = json.getChild(DATA);
if (data == null) {
System.err.println("No '" + DATA + "' section!");
return null;
}
// attributes
attributes = header.getChild(ATTRIBUTES);
if (attributes == null) {
System.err.println("No '" + ATTRIBUTES + "' array!");
return null;
}
atts = new ArrayList<Attribute>();
classAtt = new boolean[1];
classIndex = -1;
for (i = 0; i < attributes.getChildCount(); i++) {
att = toAttribute((JSONNode) attributes.getChildAt(i), classAtt);
if (att == null) {
System.err.println("Could not convert attribute #" + (i+1) + "!");
return null;
}
if (classAtt[0])
classIndex = i;
atts.add(att);
}
result = new Instances(
header.getChild(RELATION).getValue("unknown").toString(),
atts,
(onlyHeader ? 0 : data.getChildCount()));
result.setClassIndex(classIndex);
// data
if (!onlyHeader) {
for (i = 0; i < data.getChildCount(); i++) {
inst = toInstance((JSONNode) data.getChildAt(i), result);
if (inst == null) {
System.err.println("Could not convert instance #" + (i+1) + "!");
return null;
}
result.add(inst);
}
}
return result;
}
/**
* Turns a JSON object, if possible, into an Instances object.
*
* @param json the JSON object to convert
* @return the generated Instances object, null if not possible
*/
public static Instances toInstances(JSONNode json) {
return toInstances(json, false);
}
/**
* Turns a JSON object, if possible, into an Instances object (only header).
*
* @param json the JSON object to convert
* @return the generated Instances header object, null if not possible
*/
public static Instances toHeader(JSONNode json) {
return toInstances(json, true);
}
/**
* Turns the Attribute into a JSON object.
*
* @param inst the corresponding dataset
* @param att the attribute to convert
* @return the JSON object
*/
protected static JSONNode toJSON(Instances inst, Attribute att) {
JSONNode result;
JSONNode labels;
int i;
result = new JSONNode();
result.addPrimitive(NAME, att.name());
result.addPrimitive(TYPE, Attribute.typeToString(att));
result.addPrimitive(CLASS, (att.index() == inst.classIndex()));
result.addPrimitive(WEIGHT, att.weight());
if (att.isNominal()) {
labels = result.addArray(LABELS);
for (i = 0; i < att.numValues(); i++)
labels.addArrayElement(att.value(i));
}
if (att.isDate())
result.addPrimitive(DATEFORMAT, att.getDateFormat());
return result;
}
/**
* Turns the Instance into a JSON object.
*
* @param inst the Instance to convert
* @return the JSON object
*/
protected static JSONNode toJSON(Instance inst) {
JSONNode result;
JSONNode values;
int i;
boolean sparse;
result = new JSONNode();
sparse = (inst instanceof SparseInstance);
result.addPrimitive(SPARSE, sparse);
result.addPrimitive(WEIGHT, inst.weight());
values = result.addArray(VALUES);
if (sparse) {
for (i = 0; i < inst.numValues(); i++)
values.addArrayElement(inst.index(i) + SPARSE_SEPARATOR + inst.toString(inst.index(i)));
}
else {
for (i = 0; i < inst.numAttributes(); i++)
values.addArrayElement(inst.toString(i));
}
return result;
}
/**
* Turns the Instances object into a JSON object.
*
* @param inst the Instances to turn into a JSON object
* @return the JSON object
*/
public static JSONNode toJSON(Instances inst) {
JSONNode result;
JSONNode header;
JSONNode atts;
JSONNode data;
int i;
result = new JSONNode();
// header
header = result.addObject(HEADER);
header.addPrimitive(RELATION, inst.relationName());
atts = header.addArray(ATTRIBUTES);
for (i = 0; i < inst.numAttributes(); i++)
atts.add(toJSON(inst, inst.attribute(i)));
// data
data = result.addArray(DATA);
for (i = 0; i < inst.numInstances(); i++)
data.add(toJSON(inst.instance(i)));
return result;
}
/**
* For testing only.
*
* @param args expects a dataset as first parameter
* @throws Exception if something goes wrong
*/
public static void main(String[] args) throws Exception {
if (args.length != 1) {
System.err.println("No dataset supplied!");
System.exit(1);
}
// load dataset
Instances data = DataSource.read(args[0]);
// turn Instances into JSON object and output it
JSONNode json = toJSON(data);
StringBuffer buffer = new StringBuffer();
json.toString(buffer);
System.out.println(buffer.toString());
// turn JSON object back into Instances and output it
Instances inst = toInstances(json);
System.out.println(inst);
}
}