Use locational codes for random access of cells of an octree. In particular, this technique is useful for quickly finding the nearest neighbors of an arbitrary point in the octree.

Installation

]add https://github.com/alainchau/Octrees.jl

Example

julia> Using Octrees

# Generate artifical data and project onto xy-plane
julia> X = randn(3,100); X[3,:] .= 0

# Create octree
julia> octree = Octree(X);
Creating Octree with minimum side length δ = 0.02745
   
julia> using Plots
julia> include("src/misc/plotstuff.jl")
plot3d! (generic function with 2 methods)
   
julia> plot!(octree)
  
# Find nearest neighbors
julia> nn = knn(octree, [0,0,0], 1) |> collect;
julia> scatter!(X[1,nn], X[2,nn], markersize=3, color=:red)

# Draw circle to verify nearest neighbors
julia> ts = range(0.,2π,length=100)
julia> xs, ys = cos.(ts), sin.(ts)
julia> plot!(xs, ys, marker=0, fillcolor=:red, fillalpha=0.5, seriestype=:shape)

Relevant literature: http://ronaldperry.org/treeTraversalJGTWithCode.pdf