Greatly improve performance of clusterization by hinting that min/max should be performed with implied zero value

src/main/kotlin/ru/dbotthepony/mc/otm/client/render/blockentity/EnergyCounterRenderer.kt

@@ -104,7 +104,7 @@ class EnergyCounterRenderer(private val context: BlockEntityRendererProvider.Con
 
 					map[1f] = maximum.formatPower()
 
-					for (cluster in chart.asIterable().clusterize(random)) {
+					for (cluster in chart.asIterable().clusterize(random, zeroBound = true)) {
 						val perc = (cluster.center / maximum).toFloat()
 
 						if (map.keys.none { (it - perc).absoluteValue < 0.08f }) {

src/main/kotlin/ru/dbotthepony/mc/otm/core/math/Clustering.kt

@@ -90,6 +90,7 @@ private class MutableCluster<V : Comparable<V>>(var center: V) {
 private fun <V : Comparable<V>> Iterable<V>.clusterize(
 	random: RandomGenerator,
 	initialClusters: Int = 1,
+	zeroBound: Boolean = false,
 	identity: V,
 	plus: (V, V) -> V,
 	minus: (V, V) -> V,
@@ -126,8 +127,27 @@ private fun <V : Comparable<V>> Iterable<V>.clusterize(
 		cluster.values.add(wrapped)
 	}
 
+	if (zeroBound) {
+		min = minOf(min, identity)
+		max = maxOf(max, identity)
+	}
+
 	if (min == max) {
 		return listOf(Cluster.Impl(listOf(min), min))
+	} else {
+		// if "clusters" already satisfy constraints...
+		clusters.forEach { it.calculateCenter(identity, plus, minus, divInt, abs) }
+		values.forEach { it.updateError(abs, minus) }
+
+		val maxError = values.maxOf { it.error }
+
+		if (!heuristics(min, max, maxError)) {
+			return clusters.stream()
+				.filter { it.values.isNotEmpty() }
+				.map { Cluster.Impl(it.values.map { it.value }, it.center) }
+				.sorted { o1, o2 -> o2.values.size.compareTo(o1.values.size) } // большие кластеры должны идти первыми
+				.toList()
+		}
 	}
 
 	while (true) {
@@ -182,8 +202,8 @@ private fun <V : Comparable<V>> Iterable<V>.clusterize(
 // TODO: could use some tweaking
 private val DECIMAL_ERROR_TOLERANCE = Decimal("0.02")
 
-fun Iterable<Decimal>.clusterize(random: RandomGenerator, clusters: Int? = null): List<Cluster<Decimal>> {
+fun Iterable<Decimal>.clusterize(random: RandomGenerator, clusters: Int? = null, zeroBound: Boolean = false): List<Cluster<Decimal>> {
-	return clusterize(random, clusters ?: 1, Decimal.ZERO, Decimal::plus, Decimal::minus, Decimal::div, Decimal::absoluteValue) { min, max, error ->
+	return clusterize(random, clusters ?: 1, zeroBound, Decimal.ZERO, Decimal::plus, Decimal::minus, Decimal::div, Decimal::absoluteValue) { min, max, error ->
 		if (clusters != null)
 			false
 		else

src/main/kotlin/ru/dbotthepony/mc/otm/core/util/Formatting.kt

@@ -456,7 +456,7 @@ private fun formatHistoryChart(
 			val rand = java.util.Random()
 
 			if (maxTransferred.isNotZero && transferredMult > 0.2f) {
-				for (cluster in widget.transferred.clusterize(rand)) {
+				for (cluster in widget.transferred.clusterize(rand, zeroBound = true)) {
 					val perc = (cluster.center / maxTransferred).toFloat() * transferredMult
 
 					if (labelNames.keys.none { (it - perc).absoluteValue < 0.08f })
@@ -465,7 +465,7 @@ private fun formatHistoryChart(
 			}
 
 			if (maxReceived.isNotZero && receivedMult > 0.2f) {
-				for (cluster in widget.received.clusterize(rand)) {
+				for (cluster in widget.received.clusterize(rand, zeroBound = true)) {
 					val perc = zero + (cluster.center / maxReceived).toFloat() * receivedMult
 
 					if (labelNames.keys.none { (it - perc).absoluteValue < 0.08f })
@@ -473,7 +473,7 @@ private fun formatHistoryChart(
 				}
 			}
 
-			val clusters = diff.asIterable().clusterize(rand)
+			val clusters = diff.asIterable().clusterize(rand, zeroBound = true)
 
 			for (cluster in clusters) {
 				val perc: Float