experimental implementation of a citation ranking as post-ranking

method. (ranking coefficient fixed, need to be made configurable)

source/net/yacy/search/query/SnippetProcess.java

@@ -306,6 +306,10 @@ public class SnippetProcess {
             r += rentry.lapp()   << this.query.ranking.coeff_cathasapp;
         }
 
+        // apply citation count
+        //System.out.println("POSTRANKING CITATION: references = " + rentry.referencesCount() + ", inbound = " + rentry.llocal() + ", outbound = " + rentry.lother());
+        r += (128 * rentry.referencesCount() / (1 + 2 * rentry.llocal() + rentry.lother())) << 8;
+        
         // prefer hit with 'prefer' pattern
         if (this.query.prefer.matcher(rentry.url().toNormalform(true, true)).matches()) {
             r += 256 << this.query.ranking.coeff_prefer;

source/net/yacy/search/snippet/ResultEntry.java

@@ -55,6 +55,7 @@ public class ResultEntry implements Comparable<ResultEntry>, Comparator<ResultEn
     private String alternative_urlname;
     private final TextSnippet textSnippet;
     private final List<MediaSnippet> mediaSnippets;
+    private final Segment indexSegment;
     
     // statistic objects
     public long dbRetrievalTime, snippetComputationTime, ranking;
@@ -66,6 +67,7 @@ public class ResultEntry implements Comparable<ResultEntry>, Comparator<ResultEn
                        final List<MediaSnippet> mediaSnippets,
                        final long dbRetrievalTime, final long snippetComputationTime) {
         this.urlentry = urlentry;
+        this.indexSegment = indexSegment;
         this.alternative_urlstring = null;
         this.alternative_urlname = null;
         this.textSnippet = textSnippet;
@@ -155,6 +157,15 @@ public class ResultEntry implements Comparable<ResultEntry>, Comparator<ResultEn
     public int filesize() {
         return this.urlentry.size();
     }
+    public int referencesCount() {
+    	return this.indexSegment.urlCitation().count(this.urlentry.hash());
+    }
+    public int llocal() {
+    	return this.urlentry.llocal();
+    }
+    public int lother() {
+    	return this.urlentry.lother();
+    }
     public int limage() {
         return this.urlentry.limage();
     }