103 lines
2.4 KiB
Go
103 lines
2.4 KiB
Go
package random
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import (
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"math/rand"
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"time"
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)
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// ProbabilitySlice 按概率随机从切片中产生一个数据并返回命中的对象及是否未命中
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// - 当总概率小于 1 将会发生未命中的情况
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func ProbabilitySlice[T any](getProbabilityHandle func(data T) float64, data ...T) (hit T, miss bool) {
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hit, _, miss = ProbabilitySliceIndex(getProbabilityHandle, data...)
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return hit, miss
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}
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// ProbabilitySliceIndex 按概率随机从切片中产生一个数据并返回命中的对象及对象索引以及是否未命中
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// - 当总概率小于 1 将会发生未命中的情况
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func ProbabilitySliceIndex[T any](getProbabilityHandle func(data T) float64, data ...T) (hit T, index int, miss bool) {
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rd := rand.New(rand.NewSource(time.Now().UnixNano()))
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var total float64
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for _, d := range data {
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total += getProbabilityHandle(d)
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}
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scaleFactor := 1.0
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var indexLimit = len(data)
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var limitP = 0.0
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if total > 1.0 {
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scaleFactor = 1.0 / total
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} else if total < 1.0 {
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indexLimit++
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limitP = 1.0 - total
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}
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var overlayProbability []float64
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cumulativeProbability := 0.0
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for i := 0; i < indexLimit; i++ {
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if i < len(data) {
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cumulativeProbability += getProbabilityHandle(data[i]) * scaleFactor
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overlayProbability = append(overlayProbability, cumulativeProbability)
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} else {
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cumulativeProbability += limitP * scaleFactor
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overlayProbability = append(overlayProbability, cumulativeProbability)
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}
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}
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if total < 1.0 {
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overlayProbability[len(overlayProbability)-1] = 1.0
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}
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var r = rd.Float64()
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var i, count = 0, len(overlayProbability)
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for i < count {
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h := int(uint(i+count) >> 1)
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if overlayProbability[h] <= r {
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i = h + 1
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} else {
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count = h
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}
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}
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if i >= len(data) {
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return hit, -1, true
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}
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hit = data[i]
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return hit, i, false
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}
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// Probability 输入一个概率，返回是否命中
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// - 当 full 不为空时，将以 full 为基数，p 为分子，计算命中概率
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func Probability(p int, full ...int) bool {
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var f = 100
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if len(full) > 0 {
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f = full[0]
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if f <= 0 {
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f = 100
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} else if p > f {
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return true
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}
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}
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r := Int(1, f)
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return r <= p
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}
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// ProbabilityChooseOne 输入一组概率，返回命中的索引
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func ProbabilityChooseOne(ps ...int) int {
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var f int
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for _, p := range ps {
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f += p
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}
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if f <= 0 {
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panic("total probability less than or equal to 0")
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}
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r := Int(1, f)
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for i, p := range ps {
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if r <= p {
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return i
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}
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r -= p
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}
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panic("probability choose one error")
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}
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