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Improve performance and readability of recall and precision measurements #647

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8415d26
Perf optimized version of AccuracyMetrics and removal of dead and noi…
tlwillke Mar 19, 2026
5ce81ac
AccuracyMetrics now treats duplicate ground truth and retrieved resul…
tlwillke Mar 31, 2026
6c4902a
AccuracyMetrics tests, including duplicate Exceptions.
tlwillke Mar 31, 2026
8f09e3c
Added a check for null elements in the ground truth set.
tlwillke Mar 31, 2026
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117 changes: 68 additions & 49 deletions jvector-examples/src/main/java/io/github/jbellis/jvector/example/util/AccuracyMetrics.java
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Original file line number Diff line number Diff line change
Expand Up @@ -17,11 +17,9 @@
package io.github.jbellis.jvector.example.util;

import io.github.jbellis.jvector.graph.SearchResult;

import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.IntStream;
import java.util.Set;

/**
* Computes accuracy metrics, such as recall and mean average precision.
Expand All @@ -41,43 +39,54 @@ public static double recallFromSearchResults(List<? extends List<Integer>> gt, L
if (gt.size() != retrieved.size()) {
throw new IllegalArgumentException("Insufficient ground truth for the number of retrieved elements");
}
Long correctCount = IntStream.range(0, gt.size())
.mapToObj(i -> topKCorrect(gt.get(i), retrieved.get(i), kGT, kRetrieved))
.reduce(0L, Long::sum);

long correctCount = 0;
for (int i = 0; i < gt.size(); i++) {
correctCount += topKCorrect(gt.get(i), retrieved.get(i), kGT, kRetrieved);
}

return (double) correctCount / (kGT * gt.size());
}

private static long topKCorrect(List<Integer> gt, List<Integer> retrieved, int kGT, int kRetrieved) {
private static long topKCorrect(List<Integer> gt, SearchResult retrieved, int kGT, int kRetrieved) {
// Exception validation
var nodes = retrieved.getNodes();
if (kGT > kRetrieved) {
throw new IllegalArgumentException("kGT: " + kGT + " > kRetrieved: " + kRetrieved);
}
if (kGT > gt.size()) {
throw new IllegalArgumentException("kGT: " + kGT + " > Gt size: " + gt.size());
}
if (kRetrieved > retrieved.size()) {
throw new IllegalArgumentException("kRetrieved: " + kRetrieved + " > retrieved size: " + retrieved.size());
if (kRetrieved > nodes.length) {
throw new IllegalArgumentException("kRetrieved: " + kRetrieved + " > retrieved size: " + nodes.length);
}

var gtView = crop(gt, kGT);
var retrievedView = crop(retrieved, kRetrieved);

if (gtView.size() > retrieved.size()) {
return gtView.stream().filter(retrievedView::contains).count();
} else {
return retrievedView.stream().filter(gtView::contains).count();
// Build HashSet with explicit capacity to avoid rehashing.
// Load factor is 0.75, so sized to kGT / 0.75.
Set<Integer> gtSet = new HashSet<>((int) (kGT / 0.75f) + 1);
for (int i = 0; i < kGT; i++) {
Integer ord = gt.get(i);
if (ord == null) {
throw new IllegalArgumentException("Null ground truth ordinal in top-" + kGT + " at index " + i);
}
if (!gtSet.add(ord)) {
throw new IllegalArgumentException("Duplicate ground truth ordinal in top-" + kGT + ": " + ord);
}
}
}

private static long topKCorrect(List<Integer> gt, SearchResult retrieved, int kGT, int kRetrieved) {
var temp = Arrays.stream(retrieved.getNodes()).mapToInt(nodeScore -> nodeScore.node)
.boxed()
.collect(Collectors.toList());
return topKCorrect(gt, temp, kGT, kRetrieved);
}
Set<Integer> seenRetrieved = new HashSet<>((int) (kRetrieved / 0.75f) + 1);
int hits = 0;
for (int i = 0; i < kRetrieved; i++) {
int p = nodes[i].node;
if (!seenRetrieved.add(p)) {
throw new IllegalArgumentException("Duplicate retrieved ordinal in top-" + kRetrieved + ": " + p);
}
if (gtSet.contains(p)) {
hits++;
}
}

private static List<Integer> crop(List<Integer> list, int k) {
int count = Math.min(list.size(), k);
return list.subList(0, count);
return hits;
}

/**
Expand All @@ -89,33 +98,41 @@ private static List<Integer> crop(List<Integer> list, int k) {
* @return the average precision
*/
public static double averagePrecisionAtK(List<Integer> gt, SearchResult retrieved, int k) {
var retrievedTemp = Arrays.stream(retrieved.getNodes()).mapToInt(nodeScore -> nodeScore.node)
.boxed()
.collect(Collectors.toList());

var nodes = retrieved.getNodes();
if (k > gt.size()) {
throw new IllegalArgumentException("k: " + k + " > Gt size: " + gt.size());
}
if (k > retrievedTemp.size()) {
throw new IllegalArgumentException("k: " + k + " > retrieved size: " + retrievedTemp.size());
if (k > nodes.length) {
throw new IllegalArgumentException("k: " + k + " > retrieved size: " + nodes.length);
}

var gtView = crop(gt, k);
var retrievedView = crop(retrievedTemp, k);
// Sized hashset used for performance.
Set<Integer> gtSet = new HashSet<>((int) (k / 0.75f) + 1);
for (int i = 0; i < k; i++) {
Integer ord = gt.get(i);
if (ord == null) {
throw new IllegalArgumentException("Null ground truth ordinal in top-" + k + " at index " + i);
}
if (!gtSet.add(ord)) {
throw new IllegalArgumentException("Duplicate ground truth ordinal in top-" + k + ": " + ord);
}
}

Set<Integer> seenRetrieved = new HashSet<>((int) (k / 0.75f) + 1);
double score = 0.;
int num_hits = 0;
int i = 0;

for (var p : retrievedView) {
if (gtView.contains(p) && !retrievedView.subList(0, i).contains(p)) {
num_hits += 1;
score += num_hits / (i + 1.0);
int hits = 0;
for (int i = 0; i < k; i++) {
int p = nodes[i].node;
if (!seenRetrieved.add(p)) {
throw new IllegalArgumentException("Duplicate retrieved ordinal in top-" + k + ": " + p);
}
if (gtSet.contains(p)) {
hits++;
score += (double) hits / (i + 1);
}
i++;
}

return score / gtView.size();
return score / k;
}

/**
Expand All @@ -130,10 +147,12 @@ public static double meanAveragePrecisionAtK(List<? extends List<Integer>> gt, L
if (gt.size() != retrieved.size()) {
throw new IllegalArgumentException("Insufficient ground truth for the number of retrieved elements");
}
Double apk = IntStream.range(0, gt.size())
.mapToObj(i -> averagePrecisionAtK(gt.get(i), retrieved.get(i), k))
.reduce(0., Double::sum);
return apk / gt.size();
}

double totalAp = 0;
for (int i = 0; i < gt.size(); i++) {
totalAp += averagePrecisionAtK(gt.get(i), retrieved.get(i), k);
}

return totalAp / gt.size();
}
}
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