99 lines
2.0 KiB
Go
99 lines
2.0 KiB
Go
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package base
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import (
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"github.com/tidwall/tinyqueue"
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)
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type queueItem struct {
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node *treeNode
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isItem bool
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dist float64
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}
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func (item *queueItem) Less(b tinyqueue.Item) bool {
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return item.dist < b.(*queueItem).dist
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}
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// KNN returns items nearest to farthest. The dist param is the "box distance".
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func (tr *RTree) KNN(min, max []float64, center bool, iter func(item interface{}, dist float64) bool) bool {
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var isBox bool
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knnPoint := make([]float64, tr.dims)
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bbox := &treeNode{min: min, max: max}
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for i := 0; i < tr.dims; i++ {
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knnPoint[i] = (bbox.min[i] + bbox.max[i]) / 2
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if !isBox && bbox.min[i] != bbox.max[i] {
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isBox = true
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}
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}
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node := tr.data
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queue := tinyqueue.New(nil)
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for node != nil {
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for i := 0; i < node.count; i++ {
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child := node.children[i]
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var dist float64
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if isBox {
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dist = boxDistRect(bbox, child)
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} else {
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dist = boxDistPoint(knnPoint, child)
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}
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queue.Push(&queueItem{node: child, isItem: node.leaf, dist: dist})
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}
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for queue.Len() > 0 && queue.Peek().(*queueItem).isItem {
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item := queue.Pop().(*queueItem)
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if !iter(item.node.unsafeItem().item, item.dist) {
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return false
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}
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}
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last := queue.Pop()
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if last != nil {
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node = (*treeNode)(last.(*queueItem).node)
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} else {
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node = nil
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}
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}
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return true
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}
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func boxDistRect(a, b *treeNode) float64 {
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var dist float64
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for i := 0; i < len(a.min); i++ {
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var min, max float64
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if a.min[i] > b.min[i] {
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min = a.min[i]
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} else {
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min = b.min[i]
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}
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if a.max[i] < b.max[i] {
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max = a.max[i]
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} else {
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max = b.max[i]
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}
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squared := min - max
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if squared > 0 {
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dist += squared * squared
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}
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}
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return dist
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}
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func boxDistPoint(point []float64, childBox *treeNode) float64 {
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var dist float64
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for i := 0; i < len(point); i++ {
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d := axisDist(point[i], childBox.min[i], childBox.max[i])
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dist += d * d
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}
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return dist
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}
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func axisDist(k, min, max float64) float64 {
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if k < min {
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return min - k
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}
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if k <= max {
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return 0
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}
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return k - max
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}
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