01: package it.unimi.dsi.mg4j.index.cluster;
02:
03: /*
04: * MG4J: Managing Gigabytes for Java
05: *
06: * Copyright (C) 2006-2007 Sebastiano Vigna
07: *
08: * This library is free software; you can redistribute it and/or modify it
09: * under the terms of the GNU Lesser General Public License as published by the Free
10: * Software Foundation; either version 2.1 of the License, or (at your option)
11: * any later version.
12: *
13: * This library is distributed in the hope that it will be useful, but
14: * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15: * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
16: * for more details.
17: *
18: * You should have received a copy of the GNU Lesser General Public License
19: * along with this program; if not, write to the Free Software
20: * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
21: *
22: */
23:
24: import java.io.Serializable;
25:
26: /** A common ancestor interface for all clustering strategies.
27: *
28: * <p>Clustering strategies are dual to
29: * {@linkplain it.unimi.dsi.mg4j.index.cluster.PartitioningStrategy partitioning strategies}.
30: * After partitioning an index, you can see the set of its parts as local indices
31: * of a cluster. Sometimes a partitioning strategy is also a clustering strategy
32: * (see, e.g., {@link ContiguousDocumentalStrategy}
33: * and {@link ContiguousLexicalStrategy}), but
34: * sometimes a strategy serves just
35: * one purpose (see, e.g., {@link ChainedLexicalClusteringStrategy}).
36: *
37: * <p>Each local index is defined by an integer starting from 0 up to
38: * {@link #numberOfLocalIndices()} − 1.
39: *
40: * @author Sebastiano Vigna
41: */
42:
43: public interface ClusteringStrategy extends Serializable {
44:
45: /** Returns the number of local indices handled by this strategy.
46: * @return the number of local indices handled by this strategy.
47: */
48: int numberOfLocalIndices();
49: }
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