1 files changed, 114 insertions, 0 deletions
diff --git a/src/de/lmu/ifi/dbs/elki/database/relation/ProjectedView.java b/src/de/lmu/ifi/dbs/elki/database/relation/ProjectedView.java
new file mode 100644
index 00000000..190b15c6
--- /dev/null
+++ b/src/de/lmu/ifi/dbs/elki/database/relation/ProjectedView.java
@@ -0,0 +1,114 @@
+package de.lmu.ifi.dbs.elki.database.relation;
+
+import de.lmu.ifi.dbs.elki.data.projection.Projection;
+import de.lmu.ifi.dbs.elki.data.type.SimpleTypeInformation;
+import de.lmu.ifi.dbs.elki.database.Database;
+import de.lmu.ifi.dbs.elki.database.ids.DBID;
+import de.lmu.ifi.dbs.elki.database.ids.DBIDs;
+import de.lmu.ifi.dbs.elki.result.AbstractHierarchicalResult;
+import de.lmu.ifi.dbs.elki.utilities.iterator.IterableIterator;
+
+/*
+ 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/>.
+ */
+
+/**
+ * Projected relation view (non-materialized)
+ * 
+ * @author Erich Schubert
+ * 
+ * @param <IN> Vector type
+ * @param <OUT> Vector type
+ */
+public class ProjectedView<IN, OUT> extends AbstractHierarchicalResult implements Relation<OUT> {
+  /**
+   * The wrapped representation where we get the IDs from.
+   */
+  private final Relation<IN> inner;
+
+  /**
+   * The projection we use.
+   */
+  private Projection<IN, OUT> projection;
+
+  /**
+   * Constructor.
+   * 
+   * @param inner Inner relation
+   * @param projection Projection function
+   */
+  public ProjectedView(Relation<IN> inner, Projection<IN, OUT> projection) {
+    super();
+    this.inner = inner;
+    this.projection = projection;
+  }
+
+  @Override
+  public String getLongName() {
+    return "projection";
+  }
+
+  @Override
+  public String getShortName() {
+    return "projection";
+  }
+
+  @Override
+  public Database getDatabase() {
+    return inner.getDatabase();
+  }
+
+  @Override
+  public OUT get(DBID id) {
+    return projection.project(inner.get(id));
+  }
+
+  @Override
+  public void set(DBID id, OUT val) {
+    throw new UnsupportedOperationException("Projections are read-only.");
+  }
+
+  @Override
+  public void delete(DBID id) {
+    inner.delete(id);
+  }
+
+  @Override
+  public SimpleTypeInformation<OUT> getDataTypeInformation() {
+    return projection.getOutputDataTypeInformation();
+  }
+
+  @Override
+  public DBIDs getDBIDs() {
+    return inner.getDBIDs();
+  }
+
+  @Override
+  public IterableIterator<DBID> iterDBIDs() {
+    return inner.iterDBIDs();
+  }
+
+  @Override
+  public int size() {
+    return inner.size();
+  }
+}
+\ No newline at end of file