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Diffstat (limited to 'src/de/lmu/ifi/dbs/elki/datasource/filter/AbstractStreamConversionFilter.java')
| -rw-r--r-- | src/de/lmu/ifi/dbs/elki/datasource/filter/AbstractStreamConversionFilter.java | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/src/de/lmu/ifi/dbs/elki/datasource/filter/AbstractStreamConversionFilter.java b/src/de/lmu/ifi/dbs/elki/datasource/filter/AbstractStreamConversionFilter.java new file mode 100644 index 00000000..1c8acb72 --- /dev/null +++ b/src/de/lmu/ifi/dbs/elki/datasource/filter/AbstractStreamConversionFilter.java @@ -0,0 +1,117 @@ +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 de.lmu.ifi.dbs.elki.data.type.SimpleTypeInformation; +import de.lmu.ifi.dbs.elki.datasource.bundle.BundleMeta; + +/** + * Abstract base class for simple conversion filters such as normalizations and + * projections. + * + * @author Erich Schubert + * + * @param <I> Input object type + * @param <O> Input object type + */ +public abstract class AbstractStreamConversionFilter<I, O> extends AbstractStreamFilter { + /** + * The filtered meta + */ + BundleMeta meta; + + /** + * The column to filter + */ + int column = -1; + + @Override + public BundleMeta getMeta() { + return meta; + } + + @Override + public Object data(int rnum) { + if(rnum != column) { + return source.data(rnum); + } + // Convert: + @SuppressWarnings("unchecked") + final I obj = (I) source.data(rnum); + return filterSingleObject(obj); + } + + @Override + public Event nextEvent() { + Event ev = source.nextEvent(); + if(ev == Event.META_CHANGED) { + if(meta == null) { + meta = new BundleMeta(); + } + BundleMeta origmeta = source.getMeta(); + for(int i = meta.size(); i < origmeta.size(); i++) { + if(column < 0) { + @SuppressWarnings("unchecked") + SimpleTypeInformation<Object> type = (SimpleTypeInformation<Object>) origmeta.get(i); + // Test whether this type matches + if(getInputTypeRestriction().isAssignableFromType(type)) { + @SuppressWarnings("unchecked") + final SimpleTypeInformation<I> castType = (SimpleTypeInformation<I>) type; + meta.add(convertedType(castType)); + column = i; + continue; + } + } + meta.add(origmeta.get(i)); + } + } + return ev; + } + + /** + * Normalize a single instance. + * + * You can implement this as UnsupportedOperationException if you override + * both public "normalize" functions! + * + * @param obj Database object to normalize + * @return Normalized database object + */ + abstract protected O filterSingleObject(I obj); + + /** + * Get the input type restriction used for negotiating the data query. + * + * @return Type restriction + */ + abstract protected SimpleTypeInformation<? super I> getInputTypeRestriction(); + + /** + * Get the output type from the input type after conversion. + * + * @param in input type restriction + * @return output type restriction + */ + abstract protected SimpleTypeInformation<? super O> convertedType(SimpleTypeInformation<I> in); +}
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