package de.lmu.ifi.dbs.elki.datasource.filter;
/*
This file is part of ELKI:
Environment for Developing KDD-Applications Supported by Index-Structures
Copyright (C) 2012
Ludwig-Maximilians-Universität München
Lehr- und Forschungseinheit für Datenbanksysteme
ELKI Development Team
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero 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 Affero General Public License for more details.
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Comparator;
import java.util.List;
import de.lmu.ifi.dbs.elki.data.type.TypeUtil;
import de.lmu.ifi.dbs.elki.datasource.bundle.MultipleObjectsBundle;
import de.lmu.ifi.dbs.elki.logging.Logging;
/**
* A filter to sort the data set by some label.
*
* @author Erich Schubert
*
* @apiviz.uses de.lmu.ifi.dbs.elki.data.LabelList oneway - - «reads»
*/
public class SortByLabelFilter implements ObjectFilter {
/**
* Class logger
*/
private static final Logging logger = Logging.getLogger(SortByLabelFilter.class);
/**
* Constructor.
*/
public SortByLabelFilter() {
super();
}
@Override
public MultipleObjectsBundle filter(final MultipleObjectsBundle objects) {
if(logger.isDebugging()) {
logger.debug("Shuffling the data set");
}
// Prepare a reposition array for cheap resorting
final int size = objects.dataLength();
final Integer[] offsets = new Integer[size];
for(int i = 0; i < size; i++) {
offsets[i] = i;
}
// Sort by labels - identify a label column
final int lblcol;
{
int lblc = -1;
for(int i = 0; i < objects.metaLength(); i++) {
if(TypeUtil.GUESSED_LABEL.isAssignableFromType(objects.meta(i))) {
lblc = i;
break;
}
}
lblcol = lblc; // make static
}
Arrays.sort(offsets, new Comparator<Integer>() {
@Override
public int compare(Integer o1, Integer o2) {
String l1 = objects.data(o1, lblcol).toString();
String l2 = objects.data(o2, lblcol).toString();
return l1.compareToIgnoreCase(l2);
}
});
MultipleObjectsBundle bundle = new MultipleObjectsBundle();
for(int j = 0; j < objects.metaLength(); j++) {
// Reorder column accordingly
List<?> in = objects.getColumn(j);
List<Object> data = new ArrayList<Object>(size);
for(int i = 0; i < size; i++) {
data.add(in.get(offsets[i]));
}
bundle.appendColumn(objects.meta(j), data);
}
return bundle;
}
}