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Posted to commits@mahout.apache.org by sr...@apache.org on 2012/09/21 12:16:00 UTC

svn commit: r1388403 - /mahout/trunk/core/src/main/java/org/apache/mahout/cf/taste/impl/eval/GenericRecommenderIRStatsEvaluator.java

Author: srowen
Date: Fri Sep 21 10:16:00 2012
New Revision: 1388403

URL: http://svn.apache.org/viewvc?rev=1388403&view=rev
Log:
Prevent NaN in corner case of nDCG calculation

Modified:
    mahout/trunk/core/src/main/java/org/apache/mahout/cf/taste/impl/eval/GenericRecommenderIRStatsEvaluator.java

Modified: mahout/trunk/core/src/main/java/org/apache/mahout/cf/taste/impl/eval/GenericRecommenderIRStatsEvaluator.java
URL: http://svn.apache.org/viewvc/mahout/trunk/core/src/main/java/org/apache/mahout/cf/taste/impl/eval/GenericRecommenderIRStatsEvaluator.java?rev=1388403&r1=1388402&r2=1388403&view=diff
==============================================================================
--- mahout/trunk/core/src/main/java/org/apache/mahout/cf/taste/impl/eval/GenericRecommenderIRStatsEvaluator.java (original)
+++ mahout/trunk/core/src/main/java/org/apache/mahout/cf/taste/impl/eval/GenericRecommenderIRStatsEvaluator.java Fri Sep 21 10:16:00 2012
@@ -191,7 +191,9 @@ public final class GenericRecommenderIRS
           idealizedGain += discount;
         }
       }
-      nDCG.addDatum(cumulativeGain / idealizedGain);
+      if (idealizedGain > 0.0) {
+        nDCG.addDatum(cumulativeGain / idealizedGain);
+      }
       
       // Reach
       numUsersRecommendedFor++;