configure rcf with new minimum samples

src/main/java/com/amazon/opendistroforelasticsearch/ad/AnomalyDetectorPlugin.java

@@ -290,6 +290,7 @@ public Collection<Object> createComponents(
             AnomalyDetectorSettings.NUM_TREES,
             AnomalyDetectorSettings.NUM_SAMPLES_PER_TREE,
             AnomalyDetectorSettings.TIME_DECAY,
+            AnomalyDetectorSettings.NUM_MIN_SAMPLES,
             AnomalyDetectorSettings.THRESHOLD_MIN_PVALUE,
             AnomalyDetectorSettings.THRESHOLD_MAX_RANK_ERROR,
             AnomalyDetectorSettings.THRESHOLD_MAX_SCORE,

src/main/java/com/amazon/opendistroforelasticsearch/ad/ml/ModelManager.java

@@ -91,6 +91,7 @@ public String getName() {
     private final int rcfNumTrees;
     private final int rcfNumSamplesInTree;
     private final double rcfTimeDecay;
+    private final int rcfNumMinSamples;
     private final double thresholdMinPvalue;
     private final double thresholdMaxRankError;
     private final double thresholdMaxScore;
@@ -130,6 +131,7 @@ public String getName() {
      * @param rcfNumTrees number of trees used in RCF
      * @param rcfNumSamplesInTree number of samples in a RCF tree
      * @param rcfTimeDecay time decay for RCF
+     * @param rcfNumMinSamples minimum samples for RCF to score
      * @param thresholdMinPvalue min P-value for thresholding
      * @param thresholdMaxRankError  max rank error for thresholding
      * @param thresholdMaxScore max RCF score to thresholding
@@ -154,6 +156,7 @@ public ModelManager(
         int rcfNumTrees,
         int rcfNumSamplesInTree,
         double rcfTimeDecay,
+        int rcfNumMinSamples,
         double thresholdMinPvalue,
         double thresholdMaxRankError,
         double thresholdMaxScore,
@@ -179,6 +182,7 @@ public ModelManager(
         this.rcfNumTrees = rcfNumTrees;
         this.rcfNumSamplesInTree = rcfNumSamplesInTree;
         this.rcfTimeDecay = rcfTimeDecay;
+        this.rcfNumMinSamples = rcfNumMinSamples;
         this.thresholdMinPvalue = thresholdMinPvalue;
         this.thresholdMaxRankError = thresholdMaxRankError;
         this.thresholdMaxScore = thresholdMaxScore;
@@ -679,7 +683,7 @@ public void trainModel(AnomalyDetector anomalyDetector, double[][] dataPoints) {
                 .sampleSize(rcfNumSamplesInTree)
                 .numberOfTrees(forestSize)
                 .lambda(rcfTimeDecay)
-                .outputAfter(rcfNumSamplesInTree)
+                .outputAfter(rcfNumMinSamples)
                 .parallelExecutionEnabled(false)
                 .build();
             for (int j = 0; j < dataPoints.length; j++) {
@@ -771,7 +775,7 @@ private void trainModelForStep(
                 .sampleSize(rcfNumSamplesInTree)
                 .numberOfTrees(forestSize)
                 .lambda(rcfTimeDecay)
-                .outputAfter(rcfNumSamplesInTree)
+                .outputAfter(rcfNumMinSamples)
                 .parallelExecutionEnabled(false)
                 .build();
             for (int j = 0; j < dataPoints.length; j++) {

src/main/java/com/amazon/opendistroforelasticsearch/ad/settings/AnomalyDetectorSettings.java

@@ -159,6 +159,8 @@ private AnomalyDetectorSettings() {}
 
     public static final double TIME_DECAY = 0.0001;
 
+    public static final int NUM_MIN_SAMPLES = 128;
+
     public static final double DESIRED_MODEL_SIZE_PERCENTAGE = 0.0002;
 
     public static final double MODEL_MAX_SIZE_PERCENTAGE = 0.1;

src/test/java/com/amazon/opendistroforelasticsearch/ad/ml/ModelManagerTests.java

@@ -110,6 +110,7 @@ public class ModelManagerTests {
     private int numSamples;
     private int numFeatures;
     private double rcfTimeDecay;
+    private int numMinSamples;
     private double thresholdMinPvalue;
     private double thresholdMaxRankError;
     private double thresholdMaxScore;
@@ -143,6 +144,7 @@ public void setup() {
         numSamples = 10;
         numFeatures = 1;
         rcfTimeDecay = 1.0 / 1024;
+        numMinSamples = 1;
         thresholdMinPvalue = 0.95;
         thresholdMaxRankError = 1e-4;
         thresholdMaxScore = 8.0;
@@ -174,6 +176,7 @@ public void setup() {
                 numTrees,
                 numSamples,
                 rcfTimeDecay,
+                numMinSamples,
                 thresholdMinPvalue,
                 thresholdMaxRankError,
                 thresholdMaxScore,