Stats.kt
/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.benchmark
import android.os.Bundle
import androidx.annotation.RestrictTo
import kotlin.math.pow
import kotlin.math.roundToLong
import kotlin.math.sqrt
/**
* Provides statistics such as mean, median, min, max, and percentiles, given a list of input
* values.
*/
@RestrictTo(RestrictTo.Scope.LIBRARY_GROUP)
public class Stats(data: LongArray, public val name: String) {
public val median: Long
public val medianIndex: Int
public val min: Long
public val minIndex: Int
public val max: Long
public val maxIndex: Int
public val standardDeviation: Double
init {
val values = data.sorted()
val size = values.size
require(size >= 1) { "At least one result is necessary." }
val mean: Double = data.average()
min = values.first()
max = values.last()
median = getPercentile(values, 50)
minIndex = data.indexOf(min)
maxIndex = data.indexOf(max)
medianIndex = data.size / 2
standardDeviation = if (data.size == 1) {
0.0
} else {
val sum = values.map { (it - mean).pow(2) }.sum()
sqrt(sum / (size - 1).toDouble())
}
}
internal fun getSummary(): String {
return "Stats for $name: median $median, min $min, max $max, " +
"standardDeviation: $standardDeviation"
}
public fun putInBundle(status: Bundle, prefix: String) {
if (name == "timeNs") {
// compatibility naming scheme.
// should be removed, once we timeNs_min has been in dashboard for several weeks
status.putLong("${prefix}min", min)
status.putLong("${prefix}median", median)
status.putLong("${prefix}standardDeviation", standardDeviation.toLong())
}
// format string to be in instrumentation results format
val bundleName = name.toOutputMetricName()
status.putLong("${prefix}${bundleName}_min", min)
status.putLong("${prefix}${bundleName}_median", median)
status.putLong("${prefix}${bundleName}_stddev", standardDeviation.toLong())
}
// NOTE: Studio-generated, re-generate if members change
override fun equals(other: Any?): Boolean {
if (this === other) return true
if (javaClass != other?.javaClass) return false
other as Stats
if (name != other.name) return false
if (median != other.median) return false
if (medianIndex != other.medianIndex) return false
if (min != other.min) return false
if (minIndex != other.minIndex) return false
if (max != other.max) return false
if (maxIndex != other.maxIndex) return false
if (standardDeviation != other.standardDeviation) return false
return true
}
override fun hashCode(): Int {
var result = name.hashCode()
result = 31 * result + median.hashCode()
result = 31 * result + medianIndex
result = 31 * result + min.hashCode()
result = 31 * result + minIndex
result = 31 * result + max.hashCode()
result = 31 * result + maxIndex
result = 31 * result + standardDeviation.hashCode()
return result
}
internal companion object {
internal fun lerp(a: Long, b: Long, ratio: Double): Long {
return (a * (1 - ratio) + b * (ratio)).roundToLong()
}
internal fun getPercentile(data: List<Long>, percentile: Int): Long {
val idealIndex = percentile.coerceIn(0, 100) / 100.0 * (data.size - 1)
val firstIndex = idealIndex.toInt()
val secondIndex = firstIndex + 1
val firstValue = data[firstIndex]
val secondValue = data.getOrElse(secondIndex) { firstValue }
return lerp(firstValue, secondValue, idealIndex - firstIndex)
}
}
}