Index: trunk/CrossPare/src/de/ugoe/cs/cpdp/versions/MinClassNumberFilter.java
===================================================================
--- trunk/CrossPare/src/de/ugoe/cs/cpdp/versions/MinClassNumberFilter.java	(revision 26)
+++ trunk/CrossPare/src/de/ugoe/cs/cpdp/versions/MinClassNumberFilter.java	(revision 26)
@@ -0,0 +1,39 @@
+package de.ugoe.cs.cpdp.versions;
+
+import weka.core.Instances;
+
+/**
+ * Applies to small data sets. All data sets that do not have the required minimal number of instances in each class (i.e., positive, negative) are removed. 
+ * @author Steffen Herbold
+ */
+public class MinClassNumberFilter extends AbstractVersionFilter {
+
+	/**
+	 * minimal number of instances required
+	 */
+	private int minInstances = 0;
+	
+	/**
+	 * @see de.ugoe.cs.cpdp.versions.IVersionFilter#apply(de.ugoe.cs.cpdp.versions.SoftwareVersion)
+	 */
+	@Override
+	public boolean apply(SoftwareVersion version) {
+		Instances instances = version.getInstances();
+		int[] counts = instances.attributeStats(instances.classIndex()).nominalCounts;
+		boolean toSmall = false;
+		for( int count : counts ) {
+			toSmall |= count<minInstances;
+		}
+		return toSmall;
+	}
+
+	/**
+	 * Sets the minimal number of instances for each class.
+	 * @param parameters number of instances
+	 */
+	@Override
+	public void setParameter(String parameters) {
+		minInstances = Integer.parseInt(parameters);
+	}
+
+}