feat: only compute std dev on components that output values

Fixes #94
metacosm · Jul 9, 2024 · cc59f1a · cc59f1a
1 parent ef55607
commit cc59f1a
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Showing 2 changed files with 24 additions and 8 deletions.
diff --git a/measure/src/main/java/net/laprun/sustainability/power/measure/OngoingPowerMeasure.java b/measure/src/main/java/net/laprun/sustainability/power/measure/OngoingPowerMeasure.java
@@ -1,7 +1,8 @@
 package net.laprun.sustainability.power.measure;
 
 import java.time.Duration;
-import java.util.stream.IntStream;
+import java.util.HashSet;
+import java.util.Set;
 
 import org.apache.commons.math3.stat.descriptive.DescriptiveStatistics;
 
@@ -13,6 +14,7 @@ public class OngoingPowerMeasure implements PowerMeasure {
     private final DescriptiveStatistics total;
     private final long startedAt;
     private final double[] averages;
+    private final Set<Integer> nonZeroComponents;
     private double minTotal = Double.MAX_VALUE;
     private double maxTotal;
     private int samples;
@@ -25,10 +27,12 @@ public OngoingPowerMeasure(SensorMetadata sensorMetadata, Duration duration, Dur
 
         final var initialWindow = (int) (duration.toMillis() / frequency.toMillis());
         total = new DescriptiveStatistics(initialWindow);
-        this.measures = new DescriptiveStatistics[sensorMetadata.componentCardinality()];
+        this.measures = new DescriptiveStatistics[numComponents];
         for (int i = 0; i < measures.length; i++) {
             measures[i] = new DescriptiveStatistics(initialWindow);
         }
+
+        nonZeroComponents = new HashSet<>(numComponents);
     }
 
     @Override
@@ -46,6 +50,10 @@ public void recordMeasure(double[] components) {
         samples++;
         for (int component = 0; component < components.length; component++) {
             final var componentValue = components[component];
+            // record that the value is not zero
+            if (componentValue != 0) {
+                nonZeroComponents.add(component);
+            }
             measures[component].addValue(componentValue);
             averages[component] = averages[component] == 0 ? componentValue
                     : (previousSize * averages[component] + componentValue) / samples;
@@ -89,7 +97,7 @@ public double[] averagesPerComponent() {
     public StdDev standardDeviations() {
         final var cardinality = sensorMetadata.componentCardinality();
         final var stdDevs = new double[cardinality];
-        IntStream.range(0, cardinality)
+        nonZeroComponents.stream()
                 .parallel()
                 .forEach(component -> stdDevs[component] = measures[component].getStandardDeviation());
 

diff --git a/measure/src/test/java/net/laprun/sustainability/power/measure/OngoingPowerMeasureTest.java b/measure/src/test/java/net/laprun/sustainability/power/measure/OngoingPowerMeasureTest.java
@@ -15,34 +15,40 @@ public class OngoingPowerMeasureTest {
     void testStatistics() {
         final var m1c1 = 10.0;
         final var m1c2 = 12.0;
+        final var m1c3 = 0.0;
         final var m2c1 = 8.0;
         final var m2c2 = 17.0;
+        final var m2c3 = 0.0;
         final var metadata = new SensorMetadata(Map.of(), null, new int[0]) {
 
             @Override
             public int componentCardinality() {
-                return 2;
+                return 3;
             }
         };
         final var measure = new OngoingPowerMeasure(metadata, Duration.ofSeconds(1), Duration.ofMillis(500));
 
         final var components = new double[metadata.componentCardinality()];
         components[0] = m1c1;
         components[1] = m1c2;
+        components[2] = m1c3;
         measure.recordMeasure(components);
 
         components[0] = m2c1;
         components[1] = m2c2;
+        components[2] = m2c3;
         measure.recordMeasure(components);
 
-        assertEquals(m1c1 + m1c2 + m2c1 + m2c2, measure.total());
-        assertEquals((m1c1 + m1c2 + m2c1 + m2c2) / 2, measure.average());
-        assertEquals(Math.min(m1c1 + m1c2, m2c1 + m2c2), measure.minMeasuredTotal());
-        assertEquals(Math.max(m1c1 + m1c2, m2c1 + m2c2), measure.maxMeasuredTotal());
+        assertEquals(m1c1 + m1c2 + m2c1 + m2c2 + m1c3 + m2c3, measure.total());
+        assertEquals((m1c1 + m1c2 + m2c1 + m2c2 + m1c3 + m2c3) / 2, measure.average());
+        assertEquals(Math.min(m1c1 + m1c2 + m1c3, m2c1 + m2c2 + m2c3), measure.minMeasuredTotal());
+        assertEquals(Math.max(m1c1 + m1c2 + m1c3, m2c1 + m2c2 + m2c3), measure.maxMeasuredTotal());
         final var c1Avg = measure.averagesPerComponent()[0];
         final var c2Avg = measure.averagesPerComponent()[1];
+        final var c3Avg = measure.averagesPerComponent()[2];
         assertEquals((m1c1 + m2c1) / 2, c1Avg);
         assertEquals((m1c2 + m2c2) / 2, c2Avg);
+        assertEquals(0, c3Avg);
 
         final var stdVarForC1 = Math.sqrt((Math.pow(m1c1 - c1Avg, 2) + Math.pow(m2c1 - c1Avg, 2)) / (2 - 1));
         final var stdVarForC2 = Math.sqrt((Math.pow(m1c2 - c2Avg, 2) + Math.pow(m2c2 - c2Avg, 2)) / (2 - 1));
@@ -51,5 +57,7 @@ public int componentCardinality() {
                 "Standard Deviation did not match the expected value");
         assertEquals(stdVarForC2, measure.standardDeviations().perComponent()[1], 0.0001,
                 "Standard Deviation did not match the expected value");
+        assertEquals(0, measure.standardDeviations().perComponent()[2], 0.0001,
+                "Standard Deviation did not match the expected value");
     }
 }