X-Git-Url: http://jsfdemo.indexdata.com/?a=blobdiff_plain;f=src%2Frelevance.c;h=b4177c06d3a92f222dcc20887225b1df4ec29c37;hb=6bd7fce99de886558fa6d3770ec9d866b5e37ef8;hp=bc841e4e5e18396ee988824eb57343ca545a0205;hpb=8ca1269eac32c1ddc19d16dc4f74e9a1e3e0b8f9;p=pazpar2-moved-to-github.git

diff --git a/src/relevance.c b/src/relevance.c
index bc841e4..b4177c0 100644
--- a/src/relevance.c
+++ b/src/relevance.c
@@ -1,5 +1,22 @@
-/*
- * $Id: relevance.c,v 1.8 2007-01-15 04:34:28 quinn Exp $
+/* $Id: relevance.c,v 1.11 2007-05-01 05:04:53 quinn Exp $
+   Copyright (c) 2006-2007, Index Data.
+
+This file is part of Pazpar2.
+
+Pazpar2 is free software; you can redistribute it and/or modify it under
+the terms of the GNU General Public License as published by the Free
+Software Foundation; either version 2, or (at your option) any later
+version.
+
+Pazpar2 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 General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with Pazpar2; see the file LICENSE.  If not, write to the
+Free Software Foundation, 59 Temple Place - Suite 330, Boston, MA
+02111-1307, USA.
  */
 
 #include <ctype.h>
@@ -46,6 +63,7 @@ static struct word_trie *create_word_trie_node(NMEM nmem)
 
 static void word_trie_addterm(NMEM nmem, struct word_trie *n, const char *term, int num)
 {
+
     while (*term) {
         int c = tolower(*term);
         if (c < 'a' || c > 'z')
@@ -214,7 +232,17 @@ void relevance_prepare_read(struct relevance *rel, struct reclist *reclist)
         if (!rel->doc_frequency_vec[i])
             idfvec[i] = 0;
         else
-            idfvec[i] = log((float) rel->doc_frequency_vec[0] / rel->doc_frequency_vec[i]);
+        {
+            // This conditional may be terribly wrong
+            // It was there to address the situation where vec[0] == vec[i]
+            // which leads to idfvec[i] == 0... not sure about this
+            // Traditional TF-IDF may assume that a word that occurs in every
+            // record is irrelevant, but this is actually something we will
+            // see a lot
+            if ((idfvec[i] = log((float) rel->doc_frequency_vec[0] /
+                            rel->doc_frequency_vec[i])) < 0.0000001)
+                idfvec[i] = 1;
+        }
     }
     // Calculate relevance for each document
     for (i = 0; i < reclist->num_records; i++)