Fix issue #32, throw exception when instance without target value is

found.

Author: johann-petrak

src/gate/plugin/learningframework/LF_TrainClassification.java

@@ -178,9 +178,15 @@ public Document process(Document doc) {
     // This makes sure that for training, any attribute which makes use of the internal class feature
     // will get the correct value from the training set, even if the gate.LF.target feature has
     // been set differently before this PR is run.
+    // While we are at it, we also check that the target feature actually has a non-null
+    // value. We throw an exception if there is an instance without a target value!
     for(Annotation inst : instanceAS) {
       FeatureMap fm = inst.getFeatures();
-      fm.put("gate.LF.target",fm.get(getTargetFeature()));
+      Object targetVal = fm.get(getTargetFeature());
+      if(null==targetVal) {
+        throw new GateRuntimeException("Target value is null in document "+document.getName()+" for instance "+inst);
+      }
+      fm.put("gate.LF.target",targetVal);
     }
 
 

src/gate/plugin/learningframework/LF_TrainRegression.java

@@ -19,13 +19,15 @@
  */
 package gate.plugin.learningframework;
 
+import gate.Annotation;
 import gate.AnnotationSet;
 import java.net.URL;
 
 import org.apache.log4j.Logger;
 
 import gate.Controller;
 import gate.Document;
+import gate.FeatureMap;
 import gate.creole.metadata.CreoleParameter;
 import gate.creole.metadata.CreoleResource;
 import gate.creole.metadata.Optional;
@@ -154,6 +156,14 @@ public Document process(Document doc) {
     // the sequenceAS is always null for the regression task!
     // the nameFeatureName is always null for now!
     String nameFeatureName = null;
+    for(Annotation inst : instanceAS) {
+      FeatureMap fm = inst.getFeatures();
+      Object targetVal = fm.get(getTargetFeature());
+      if(null==targetVal) {
+        throw new GateRuntimeException("Target value is null in document "+document.getName()+" for instance "+inst);
+      }
+    }
+    
     corpusRepresentation.add(instanceAS, null, inputAS, null, getTargetFeature(), TargetType.NUMERIC, instanceWeightFeature, nameFeatureName, null);
     return doc;
   }