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/*
* This file is part of Go Responsiveness.
*
* Go Responsiveness is free software: you can redistribute it and/or modify it under
* the terms of the GNU General Public License as published by the Free Software Foundation,
* either version 2 of the License, or (at your option) any later version.
* Go Responsiveness is distributed in the hope that it will be useful, but WITHOUT ANY
* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE. See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with Go Responsiveness. If not, see <https://www.gnu.org/licenses/>.
*/
package utilities
import (
"math"
"sort"
"golang.org/x/exp/constraints"
"golang.org/x/exp/slices"
)
type Number interface {
constraints.Float | constraints.Integer
}
func CalculateAverage[T Number](elements []T) float64 {
total := T(0)
for i := 0; i < len(elements); i++ {
total += elements[i]
}
return float64(total) / float64(len(elements))
}
func CalculatePercentile[T Number](
elements []T,
p int,
) (result T) {
result = T(0)
if p < 0 || p > 100 {
return
}
sort.Slice(elements, func(l int, r int) bool { return elements[l] < elements[r] })
pindex := int64((float64(p) / float64(100)) * float64(len(elements)))
result = elements[pindex]
return
}
func Max(x, y uint64) uint64 {
if x > y {
return x
}
return y
}
func SignedPercentDifference[T constraints.Float | constraints.Integer](
current T,
previous T,
) (difference float64) {
fCurrent := float64(current)
fPrevious := float64(previous)
return ((fCurrent - fPrevious) / fPrevious) * 100.0
}
func AbsPercentDifference(
current float64,
previous float64,
) (difference float64) {
return (math.Abs(current-previous) / (float64(current+previous) / 2.0)) * float64(
100,
)
}
func CalculateStandardDeviation[T constraints.Float | constraints.Integer](elements []T) float64 {
// From https://www.mathsisfun.com/data/standard-deviation-calculator.html
// Yes, for real!
// Calculate the average of the numbers ...
average := CalculateAverage(elements)
// Calculate the square of each of the elements' differences from the mean.
differences_squared := make([]float64, len(elements))
for index, value := range elements {
differences_squared[index] = math.Pow(float64(value-T(average)), 2)
}
// The variance is the average of the squared differences.
// So, we need to ...
// Accumulate all those squared differences.
sds := float64(0)
for _, dss := range differences_squared {
sds += dss
}
// And then divide that total by the number of elements
variance := sds / float64(len(elements))
// Finally, the standard deviation is the square root
// of the variance.
sd := float64(math.Sqrt(variance))
// sd := T(variance)
return sd
}
func AllSequentialIncreasesLessThan[T Number](elements []T, limit float64) (bool, float64) {
if len(elements) < 2 {
return false, 0.0
}
maximumSequentialIncrease := float64(0)
for i := 1; i < len(elements); i++ {
current := elements[i]
previous := elements[i-1]
percentChange := SignedPercentDifference(current, previous)
if percentChange > limit {
return false, percentChange
}
if percentChange > float64(maximumSequentialIncrease) {
maximumSequentialIncrease = percentChange
}
}
return true, maximumSequentialIncrease
}
// elements must already be sorted!
func TrimBy[T Number](elements []T, trim int) []T {
numberToKeep := int(float32(len(elements)) * (float32(trim) / 100.0))
return elements[:numberToKeep]
}
func TrimmedMean[T Number](elements []T, trim int) (float64, []T) {
sortedElements := make([]T, len(elements))
copy(sortedElements, elements)
slices.Sort(sortedElements)
trimmedElements := TrimBy(sortedElements, trim)
return CalculateAverage(trimmedElements), trimmedElements
}
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