98 lines
2.5 KiB
Go
98 lines
2.5 KiB
Go
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package base
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import "math"
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// Load bulk load items into the R-tree.
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func (tr *RTree) Load(mins, maxs [][]float64, items []interface{}) {
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if len(items) < tr.minEntries {
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for i := 0; i < len(items); i++ {
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tr.Insert(mins[i], maxs[i], items[i])
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}
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return
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}
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// prefill the items
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fitems := make([]*treeNode, len(items))
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for i := 0; i < len(items); i++ {
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item := &treeItem{min: mins[i], max: maxs[i], item: items[i]}
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fitems[i] = item.unsafeNode()
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}
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// following equations are defined in the paper describing OMT
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N := len(fitems)
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M := tr.maxEntries
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h := int(math.Ceil(math.Log(float64(N)) / math.Log(float64(M))))
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Nsubtree := int(math.Pow(float64(M), float64(h-1)))
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S := int(math.Ceil(math.Sqrt(float64(N) / float64(Nsubtree))))
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// sort by the initial axis
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axis := 0
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sortByAxis(fitems, axis)
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// build the root node. it's split differently from the subtrees.
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children := make([]*treeNode, 0, S)
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for i := 0; i < S; i++ {
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var part []*treeNode
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if i == S-1 {
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// last split
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part = fitems[len(fitems)/S*i:]
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} else {
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part = fitems[len(fitems)/S*i : len(fitems)/S*(i+1)]
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}
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children = append(children, tr.omt(part, h-1, axis+1))
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}
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node := tr.createNode(children)
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node.leaf = false
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node.height = h
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tr.calcBBox(node)
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if tr.data.count == 0 {
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// save as is if tree is empty
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tr.data = node
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} else if tr.data.height == node.height {
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// split root if trees have the same height
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tr.splitRoot(tr.data, node)
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} else {
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if tr.data.height < node.height {
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// swap trees if inserted one is bigger
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tr.data, node = node, tr.data
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}
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// insert the small tree into the large tree at appropriate level
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tr.insert(node, nil, tr.data.height-node.height-1, true)
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}
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}
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func (tr *RTree) omt(fitems []*treeNode, h, axis int) *treeNode {
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if len(fitems) <= tr.maxEntries {
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// reached leaf level; return leaf
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children := make([]*treeNode, len(fitems))
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copy(children, fitems)
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node := tr.createNode(children)
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node.height = h
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tr.calcBBox(node)
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return node
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}
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// sort the items on a different axis than the previous level.
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sortByAxis(fitems, axis%tr.dims)
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children := make([]*treeNode, 0, tr.maxEntries)
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partsz := len(fitems) / tr.maxEntries
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for i := 0; i < tr.maxEntries; i++ {
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var part []*treeNode
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if i == tr.maxEntries-1 {
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// last part
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part = fitems[partsz*i:]
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} else {
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part = fitems[partsz*i : partsz*(i+1)]
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}
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children = append(children, tr.omt(part, h-1, axis+1))
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}
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node := tr.createNode(children)
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node.height = h
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node.leaf = false
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tr.calcBBox(node)
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return node
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}
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