mirror of
https://github.com/yacy/yacy_search_server.git
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3c7220bc7b
used for rwi ranking. Main changes: - introduce a posintext() to access the stored value. This reduces also mem alloc of position array for WordReferenceRow (index access) - use the positions() array for joined references on multi-word queries if needed (otherwise allow positions() to be null - adjust assignments and the min() max() and distance() calculation accordingly
69 lines
2.4 KiB
Java
69 lines
2.4 KiB
Java
// AbstractReference.java
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// (C) 2009 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
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// first published 14.04.2009 on http://yacy.net
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//
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// This is a part of YaCy, a peer-to-peer based web search engine
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//
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// $LastChangedDate$
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// $LastChangedRevision$
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// $LastChangedBy$
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//
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// LICENSE
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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package net.yacy.kelondro.rwi;
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import java.util.Iterator;
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import net.yacy.cora.util.ConcurrentLog;
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public abstract class AbstractReference implements Reference {
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/**
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* The average distance (in words) between search query terms for multi word searches.
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* @return word distance
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*/
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@Override
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public int distance() {
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// check if positions have been joined
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if (positions() == null || positions().isEmpty()) return 0;
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int d = 0;
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Iterator<Integer> i = positions().iterator();
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int s0 = posintext(); // init with own positon
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int s1;
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while (i.hasNext()) {
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s1 = i.next();
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if (s0 > 0) d += Math.abs(s0 - s1);
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s0 = s1;
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}
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// despite first line checks for size < 2 Arithmetic exception div by zero occured (1.91/9278 2016-10-19)
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// added d == 0 condition as protection for this (which was in all above tests the case)
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try {
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return d == 0 ? 0 : d / positions().size();
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} catch (ArithmeticException ex) {
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ConcurrentLog.fine("AbstractReference", "word distance calculation:" + ex.getMessage());
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return 0;
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}
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}
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@Override
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public boolean isOlder(final Reference other) {
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if (other == null) return false;
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if (this.lastModified() < other.lastModified()) return true;
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return false;
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}
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}
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