Hi list !
Can someone explain me better what the following code do ? That's
the code of OPICScoringFilter.java. Can I change it and change the
scoring when the results are displayed by adding the value of a
META TAG ? Please it's very difficult for me to progam my own
plugin so I need your help.
This is the code :
package org.apache.nutch.scoring.opic;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.List;
// Commons Logging imports
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.Text;
import org.apache.lucene.document.Document;
import org.apache.nutch.crawl.CrawlDatum;
import org.apache.nutch.crawl.Inlinks;
import org.apache.nutch.fetcher.Fetcher;
import org.apache.nutch.metadata.Metadata;
import org.apache.nutch.metadata.Nutch;
import org.apache.nutch.parse.Parse;
import org.apache.nutch.parse.ParseData;
import org.apache.nutch.protocol.Content;
import org.apache.nutch.scoring.ScoringFilter;
import org.apache.nutch.scoring.ScoringFilterException;
import org.apache.nutch.util.LogUtil;
/**
* This plugin implements a variant of an Online Page Importance
Computation
* (OPIC) score, described in this paper:
* <a href="http://www2003.org/cdrom/papers/refereed/p007/p7-
abiteboul.html"/>
* Abiteboul, Serge and Preda, Mihai and Cobena, Gregory (2003),
* Adaptive On-Line Page Importance Computation
* </a>.
*
* @author Andrzej Bialecki
*/
public class OPICScoringFilter implements ScoringFilter {
private final static Log LOG = LogFactory.getLog
(OPICScoringFilter.class);
private Configuration conf;
private float scoreInjected;
private float scorePower;
private float internalScoreFactor;
private float externalScoreFactor;
private boolean countFiltered;
public Configuration getConf() {
return conf;
}
public void setConf(Configuration conf) {
this.conf = conf;
scoreInjected = conf.getFloat("db.score.injected", 1.0f);
scorePower = conf.getFloat("indexer.score.power", 0.5f);
internalScoreFactor = conf.getFloat("db.score.link.internal",
1.0f);
externalScoreFactor = conf.getFloat("db.score.link.external",
1.0f);
countFiltered = conf.getBoolean("db.score.count.filtered", false);
}
/** Set to the value defined in config, 1.0f by default. */
public void injectedScore(Text url, CrawlDatum datum) throws
ScoringFilterException {
datum.setScore(scoreInjected);
}
/** Set to 0.0f (unknown value) - inlink contributions will bring
it to
* a correct level. Newly discovered pages have at least one
inlink. */
public void initialScore(Text url, CrawlDatum datum) throws
ScoringFilterException {
datum.setScore(0.0f);
}
/** Use [EMAIL PROTECTED] CrawlDatum#getScore()}. */
public float generatorSortValue(Text url, CrawlDatum datum, float
initSort) throws ScoringFilterException {
return datum.getScore();
}
/** Increase the score by a sum of inlinked scores. */
public void updateDbScore(Text url, CrawlDatum old, CrawlDatum
datum, List inlinked) throws ScoringFilterException {
float adjust = 0.0f;
for (int i = 0; i < inlinked.size(); i++) {
CrawlDatum linked = (CrawlDatum)inlinked.get(i);
adjust += linked.getScore();
}
if (old == null) old = datum;
datum.setScore(old.getScore() + adjust);
}
/** Store a float value of CrawlDatum.getScore() under
Fetcher.SCORE_KEY. */
public void passScoreBeforeParsing(Text url, CrawlDatum datum,
Content content) {
content.getMetadata().set(Nutch.SCORE_KEY, "" + datum.getScore());
}
/** Copy the value from Content metadata under Fetcher.SCORE_KEY
to parseData. */
public void passScoreAfterParsing(Text url, Content content,
Parse parse) {
parse.getData().getContentMeta().set(Nutch.SCORE_KEY,
content.getMetadata().get(Nutch.SCORE_KEY));
}
/** Get a float value from Fetcher.SCORE_KEY, divide it by the
number of outlinks and apply. */
public CrawlDatum distributeScoreToOutlink(Text fromUrl, Text
toUrl, ParseData parseData, CrawlDatum target, CrawlDatum adjust,
int allCount, int validCount) throws ScoringFilterException {
float score = scoreInjected;
String scoreString = parseData.getContentMeta().get
(Nutch.SCORE_KEY);
if (scoreString != null) {
try {
score = Float.parseFloat(scoreString);
} catch (Exception e) {
e.printStackTrace(LogUtil.getWarnStream(LOG));
}
}
if (countFiltered) {
score /= allCount;
} else {
score /= validCount;
}
// internal or external score factor
try {
String toHost = new URL(toUrl.toString()).getHost();
String fromHost = new URL(fromUrl.toString()).getHost();
if(toHost.equalsIgnoreCase(fromHost)){
score *= internalScoreFactor;
} else {
score *= externalScoreFactor;
}
} catch (MalformedURLException e) {
e.printStackTrace(LogUtil.getWarnStream(LOG));
score *= externalScoreFactor;
}
target.setScore(score);
// XXX (ab) no adjustment? I think this is contrary to the
algorithm descr.
// XXX in the paper, where page "loses" its score if it's
distributed to
// XXX linked pages...
return adjust;
}
/** Dampen the boost value by scorePower.*/
public float indexerScore(Text url, Document doc, CrawlDatum
dbDatum, CrawlDatum fetchDatum, Parse parse, Inlinks inlinks, float
initScore) throws ScoringFilterException {
return (float)Math.pow(dbDatum.getScore(), scorePower);
}
}
Thank's in advance,
Jisay
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