/*
* 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/>.
*/
/*
* DecisionTableHashKey.java
* Copyright (C) 2007-2012 University of Waikato, Hamilton, New Zealand
*
*/
package weka.classifiers.rules;
import java.io.Serializable;
import weka.core.Instance;
import weka.core.Instances;
import weka.core.RevisionHandler;
import weka.core.RevisionUtils;
/**
* Class providing hash table keys for DecisionTable
*/
public class DecisionTableHashKey
implements Serializable, RevisionHandler {
/** for serialization */
static final long serialVersionUID = 5674163500154964602L;
/** Array of attribute values for an instance */
private double [] attributes;
/** True for an index if the corresponding attribute value is missing. */
private boolean [] missing;
/** The key */
private int key;
/**
* Constructor for a hashKey
*
* @param t an instance from which to generate a key
* @param numAtts the number of attributes
* @param ignoreClass if true treat the class as a normal attribute
* @throws Exception if something goes wrong
*/
public DecisionTableHashKey(Instance t, int numAtts, boolean ignoreClass) throws Exception {
int i;
int cindex = t.classIndex();
key = -999;
attributes = new double [numAtts];
missing = new boolean [numAtts];
for (i=0;i<numAtts;i++) {
if (i == cindex && !ignoreClass) {
missing[i] = true;
} else {
if ((missing[i] = t.isMissing(i)) == false) {
attributes[i] = t.value(i);
}
}
}
}
/**
* Convert a hash entry to a string
*
* @param t the set of instances
* @param maxColWidth width to make the fields
* @return string representation of the hash entry
*/
public String toString(Instances t, int maxColWidth) {
int i;
int cindex = t.classIndex();
StringBuffer text = new StringBuffer();
for (i=0;i<attributes.length;i++) {
if (i != cindex) {
if (missing[i]) {
text.append("?");
for (int j=0;j<maxColWidth;j++) {
text.append(" ");
}
} else {
String ss = t.attribute(i).value((int)attributes[i]);
StringBuffer sb = new StringBuffer(ss);
for (int j=0;j < (maxColWidth-ss.length()+1); j++) {
sb.append(" ");
}
text.append(sb);
}
}
}
return text.toString();
}
/**
* Constructor for a hashKey
*
* @param t an array of feature values
*/
public DecisionTableHashKey(double [] t) {
int i;
int l = t.length;
key = -999;
attributes = new double [l];
missing = new boolean [l];
for (i=0;i<l;i++) {
if (t[i] == Double.MAX_VALUE) {
missing[i] = true;
} else {
missing[i] = false;
attributes[i] = t[i];
}
}
}
/**
* Calculates a hash code
*
* @return the hash code as an integer
*/
public int hashCode() {
int hv = 0;
if (key != -999)
return key;
for (int i=0;i<attributes.length;i++) {
if (missing[i]) {
hv += (i*13);
} else {
hv += (i * 5 * (attributes[i]+1));
}
}
if (key == -999) {
key = hv;
}
return hv;
}
/**
* Tests if two instances are equal
*
* @param b a key to compare with
* @return true if both objects are equal
*/
public boolean equals(Object b) {
if ((b == null) || !(b.getClass().equals(this.getClass()))) {
return false;
}
boolean ok = true;
boolean l;
if (b instanceof DecisionTableHashKey) {
DecisionTableHashKey n = (DecisionTableHashKey)b;
for (int i=0;i<attributes.length;i++) {
l = n.missing[i];
if (missing[i] || l) {
if ((missing[i] && !l) || (!missing[i] && l)) {
ok = false;
break;
}
} else {
if (attributes[i] != n.attributes[i]) {
ok = false;
break;
}
}
}
} else {
return false;
}
return ok;
}
/**
* Prints the hash code
*/
public void print_hash_code() {
System.out.println("Hash val: "+hashCode());
}
/**
* Returns the revision string.
*
* @return the revision
*/
public String getRevision() {
return RevisionUtils.extract("$Revision: 8034 $");
}
}