From 6a3be08c0fb5c7ad1f14168435b3de51028945d2 Mon Sep 17 00:00:00 2001
From: Adam Dickmeiss <adam@indexdata.dk>
Date: Wed, 4 Nov 2009 12:48:12 +0100
Subject: [PATCH] Deal with empty fields for ranking

Avoid division by length=0 in relevance_countwords.
---
 src/relevance.c       |    3 ++-
 test/test_http_18.res |   30 +++++++++++++++---------------
 2 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/src/relevance.c b/src/relevance.c
index 072a894..c88676e 100644
--- a/src/relevance.c
+++ b/src/relevance.c
@@ -114,7 +114,8 @@ void relevance_countwords(struct relevance *r, struct record_cluster *cluster,
 
     for (i = 1; i < r->vec_len; i++)
     {
-        cluster->term_frequency_vecf[i] += (double) mult[i] / length;
+        if (length > 0) /* only add if non-empty */
+            cluster->term_frequency_vecf[i] += (double) mult[i] / length;
         cluster->term_frequency_vec[i] += mult[i];
     }
 
diff --git a/test/test_http_18.res b/test/test_http_18.res
index eb81bff..77b4469 100644
--- a/test/test_http_18.res
+++ b/test/test_http_18.res
@@ -8,15 +8,15 @@
 <num>3</num>
 <hit>
 
-<md-title>OIL/GAS DRILLING</md-title>
-<md-description>This database contains information on oil and gas drilling such as well name, operator, driller, location, depth, copies of logs run, permits, samples (cuttings, core), completion records</md-description><location id="z3950.indexdata.com/gils" name="gils">
-<md-title>OIL/GAS DRILLING</md-title>
-<md-description tag="520">This database contains information on oil and gas drilling such as well name, operator, driller, location, depth, copies of logs run, permits, samples (cuttings, core), completion records</md-description>
-<md-description tag="513">1907-PRESENT</md-description>
+<md-title>BIBLIOGRAPHY OF MAINE GEOLOGY</md-title>
+<md-description>This data base is a computer based bibliography of marine geology.  It allows searching by topic and geographic location, similar to GEOREF.  It is currently under development to replace the printed Bibliography of Marine Geology</md-description><location id="z3950.indexdata.com/gils" name="gils">
+<md-title>BIBLIOGRAPHY OF MAINE GEOLOGY</md-title>
+<md-description tag="520">This data base is a computer based bibliography of marine geology.  It allows searching by topic and geographic location, similar to GEOREF.  It is currently under development to replace the printed Bibliography of Marine Geology</md-description>
+<md-description tag="513">1692-PRESENT</md-description>
 <md-test-usersetting-2>test-usersetting-2 data: 
 </md-test-usersetting-2></location>
-<relevance>0</relevance>
-<recid>title oil gas drilling author medium book</recid>
+<relevance>9416</relevance>
+<recid>title bibliography of maine geology author medium book</recid>
 </hit>
 <hit>
 
@@ -27,19 +27,19 @@
 <md-description tag="513">1972-1978</md-description>
 <md-test-usersetting-2>test-usersetting-2 data: 
 </md-test-usersetting-2></location>
-<relevance>-2147483648</relevance>
+<relevance>0</relevance>
 <recid>title groundwater resource maps county series author medium book</recid>
 </hit>
 <hit>
 
-<md-title>BIBLIOGRAPHY OF MAINE GEOLOGY</md-title>
-<md-description>This data base is a computer based bibliography of marine geology.  It allows searching by topic and geographic location, similar to GEOREF.  It is currently under development to replace the printed Bibliography of Marine Geology</md-description><location id="z3950.indexdata.com/gils" name="gils">
-<md-title>BIBLIOGRAPHY OF MAINE GEOLOGY</md-title>
-<md-description tag="520">This data base is a computer based bibliography of marine geology.  It allows searching by topic and geographic location, similar to GEOREF.  It is currently under development to replace the printed Bibliography of Marine Geology</md-description>
-<md-description tag="513">1692-PRESENT</md-description>
+<md-title>OIL/GAS DRILLING</md-title>
+<md-description>This database contains information on oil and gas drilling such as well name, operator, driller, location, depth, copies of logs run, permits, samples (cuttings, core), completion records</md-description><location id="z3950.indexdata.com/gils" name="gils">
+<md-title>OIL/GAS DRILLING</md-title>
+<md-description tag="520">This database contains information on oil and gas drilling such as well name, operator, driller, location, depth, copies of logs run, permits, samples (cuttings, core), completion records</md-description>
+<md-description tag="513">1907-PRESENT</md-description>
 <md-test-usersetting-2>test-usersetting-2 data: 
 </md-test-usersetting-2></location>
-<relevance>9416</relevance>
-<recid>title bibliography of maine geology author medium book</recid>
+<relevance>0</relevance>
+<recid>title oil gas drilling author medium book</recid>
 </hit>
 </show>
-- 
1.7.10.4