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[MS-973] Fix sorting logic in MatchResultSet to handle equal confidence scores #1170

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meladRaouf merged 1 commit into from
May 6, 2025
Merged

[MS-973] Fix sorting logic in MatchResultSet to handle equal confidence scores #1170

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7 changes: 3 additions & 4 deletions feature/matcher/src/main/java/com/simprints/matcher/usecases/MatchResultSet.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -8,10 +8,9 @@ internal class MatchResultSet<T : MatchResultItem>(
) {
private var lowestConfidence: Float = 0f

private val treeSet = TreeSet { o1: T, o2: T ->
// Reverse order for descending sort
-1 * o1.confidence.compareTo(o2.confidence)
}
private val treeSet = TreeSet(
compareByDescending<T> { it.confidence }.thenByDescending { it.subjectId },
)

fun add(element: T): MatchResultSet<T> {
if (lowestConfidence > element.confidence) {
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@BurningAXE BurningAXE Apr 15, 2025

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Hm, am I reading this wrong or if we first add a high confidence score (say 99), then we would not add any lower results and return a list of just 1 result? Is this the behaviour that we want?

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@BurningAXE BurningAXE Apr 15, 2025

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Ah, lowestConfidence is updated only when the set is full. That's confusing...

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@alex-vt alex-vt Apr 15, 2025

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It looks like if confidence and subjectId are now a composite comparison key, so should work as intended.

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@BurningAXE BurningAXE Apr 15, 2025

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Here we are comparing confidence only. The confusion comes from the fact that lowestConfidence is initialized with 0 and updated only when the set is full.

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@meladRaouf meladRaouf Apr 16, 2025

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This is a classic LeetCode problem 🥇. If we only need the top N elements, fully sorting the entire list is unnecessary and can be avoided to enhance performance.

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19 changes: 19 additions & 0 deletions feature/matcher/src/test/java/com/simprints/matcher/usecases/MatchResultSetTest.kt
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Expand Up @@ -46,4 +46,23 @@ class MatchResultSetTest {
),
)
}

// On equal confidence scores sort by id
@Test
fun `Stores results sorted descending by confidence and id`() {
val set = MatchResultSet<FingerprintMatchResult.Item>(3)

set.add(FingerprintMatchResult.Item("4", 0.4f))
set.add(FingerprintMatchResult.Item("1", 0.4f))
set.add(FingerprintMatchResult.Item("3", 0.3f))
set.add(FingerprintMatchResult.Item("2", 0.3f))

assertThat(set.toList()).isEqualTo(
listOf(
FingerprintMatchResult.Item("4", 0.4f),
FingerprintMatchResult.Item("1", 0.4f),
FingerprintMatchResult.Item("3", 0.3f),
),
)
}
}