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KD-TREE's in ruby
require 'pp'
class KDTree
attr_reader :root
attr_reader :points
def initialize(points, dim)
@dim = dim
@root = KDNode.new(dim).parse(points)
end
def add_node(point)
@root.add(point)
end
def find(*range)
range.collect!{ |pa|
pa = Range.new(pa.first, pa.last) if pa.kind_of? Array
}
@points = []
query(range, @root)
@points
end
def query(range, node)
axis = node.axis
median = node.location[axis]
if node.left && (median >= range[axis].begin)
query(range, node.left); /* Skip left if max of left tree (median) is out of range */
end
if node.right && (median <= range[axis].end)
query(range, node.right); /* Skip right if min of right tree (median) is out of range */
end
if (0..@dim-1).all?{|ax|
range[ax].include? node.location[ax]
}
@points << node.location;
end
end
def print
@root.print
end
end
class KDNode
attr_reader :left, :right
attr_reader :location
attr_reader :axis
def initialize(dim, location=nil, left=nil, right=nil)
@dim = dim
@location = location
@left = left
@right = right
end
def parse(points, depth = 0)
@axis = depth % @dim
points = points.sort_by{|point| point[@axis]}
half = points.length / 2
@location = points[half]
@left = KDNode.new(@dim).parse(points[0..half-1], depth+1) unless half < 1
@right = KDNode.new(@dim).parse(points[half+1..-1], depth+1) unless half+1 >= points.length
self
end
def add(point)
if @location[@axis] < point[@axis]
@left ? @left.add(point) : @left = KDNode.new(point)
else
@right ? @right.add(point) : @right = KDNode.new(point)
end
end
def remove
self.parse(@left.to_a + @right.to_a, @axis)
end
def to_a
@left.to_a + [@location] + @right.to_a
end
def print(l=0)
@left.print(l+1) if @left
puts(" "*l + @location.inspect)
@right.print(l+1) if @right
end
end
a = []
10.times do |x|
10.times do |y|
10.times do |z|
a << [x, y, z]
end
end
end
tree = KDTree.new(a, 3)
tree.print
puts " -------------- "
points = tree.find([0,4], [1,4], [5,7])
pp tree.points.sort_by{|po| po[0]}
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