101 Zeilen
2.0 KiB
Go
101 Zeilen
2.0 KiB
Go
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package weightedrandom
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import "sort"
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var (
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_ sort.Interface = &wflist[int]{}
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)
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type wflist[T any] []*weightitem[T]
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func (wfl wflist[T]) Less(i, j int) bool {
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return wfl[i].adjusted < wfl[j].adjusted
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}
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func (wfl wflist[T]) Len() int {
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return len(wfl)
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}
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func (wfl wflist[T]) Swap(i, j int) {
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wfl[i], wfl[j] = wfl[j], wfl[i]
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}
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// WeightRandom is the Type for an weighted random list
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type WeightRandom[T any] struct {
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data wflist[T]
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weightFunc AdjustFunc
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randomFunc RandomFunc
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sorted bool
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totalWeight int
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adjustedWeight int
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sorti sort.Interface
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accessfunc AccessModifier
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}
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func (wr *WeightRandom[T]) reweight() {
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wr.updatetotal()
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for _, item := range wr.data {
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item.adjusted = wr.weightFunc(item.weight, wr.totalWeight)
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}
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}
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func (wr *WeightRandom[T]) sort() {
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if wr.sorted {
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return
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}
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if wr.sorti == nil {
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wr.sorti = sort.Reverse(&wr.data)
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}
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wr.reweight()
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sort.Stable(wr.sorti)
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wr.sorted = true
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}
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func (wr *WeightRandom[T]) updatetotal() {
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newtotal := 0
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newadjusted := 0
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for _, item := range wr.data {
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newtotal += item.weight
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newadjusted += item.adjusted
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}
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wr.adjustedWeight = newadjusted
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wr.totalWeight = newtotal
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}
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// AddElement adds an single Element to the list
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func (wr *WeightRandom[T]) AddElement(item T, weight int) {
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wr.sorted = false
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wr.totalWeight += weight
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wr.data = append(wr.data, &weightitem[T]{weight: weight, value: item})
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}
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// AddElements adds an list of elements to the list
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func (wr *WeightRandom[T]) AddElements(weight int, items ...T) {
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for _, item := range items {
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wr.AddElement(item, weight)
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}
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wr.reweight()
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wr.sort()
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}
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// Get returns an random value of the list of items or the null value of the type in case no element was added
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func (wr *WeightRandom[T]) Get() (t T) {
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if !wr.sorted {
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wr.reweight()
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wr.sort()
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}
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pos := wr.randomFunc(wr.data.Len())
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for _, item := range wr.data {
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pos -= item.adjusted
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if pos <= 0 {
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if wr.accessfunc != nil {
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wr.sorted = false
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item.weight = wr.accessfunc(item.weight)
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}
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return item.value
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}
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}
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return
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}
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