Kernel Density Estimate with product approximation using multiscale Gibbs sampling
Author JuliaRobotics
18 Stars
Updated Last
1 Year Ago
Started In
April 2016


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Kernel Density Estimation with product approximation using multiscale Gibbs sampling.

All code is implemented in native Julia, including plotting. The main focus of this module is the ability to take the product between multiple KDEs, and makes this module unique from other KDE implementations. This package also supports n-dimensional KDEs. Please see examples below for details. The implementation is already fairly optimized from a symbolic standpoint and is based on work by:

Sudderth, Erik B.; Ihler, Alexander, et al. "Nonparametric belief propagation." Communications of the ACM 53.10 (2010): 95-103.


In Julia 0.7 and above:

] add KernelDensityEstimate

Plotting Functions

The plotting functions for this library have been separated into KernelDensityEstimatePlotting.jl. Plotting functionality uses Gadfly. Comments welcome.


Bring the module into the workspace

using KernelDensityEstimate
# Basic one dimensional examples
# using leave-one-out likelihood cross validation for bandwidth estimation
p100 = kde!([randn(50);10.0.+2*randn(50)])
p2 = kde!([0.0;10.0],[1.0]) # multibandwidth still to be added
p75 = resample(p2,75)

# bring in the plotting functions
using KernelDensityEstimatePlotting
plot([p100;p2;p75],c=["red";"green";"blue"]) # using Gadfly under the hood

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Multidimensional example

pd2 = kde!(randn(3,100));
@time pd2 = kde!(randn(3,100)); # defaults to loocv
pm12 = marginal(pd2,[1;2]);
pm2 = marginal(pm12,[2]);

Multiscale Gibbs product approximation example

p = kde!(randn(2,100))
q = kde!(2.0.+randn(2,100))
dummy = kde!(rand(2,100),[1.0]);
mcmciters = 5
pGM, = prodAppxMSGibbsS(dummy, [p;q], nothing, nothing, Niter=mcmciters)
pq = kde!(pGM)
pq1 = marginal(pq,[1])
Pl1 = plot([marginal(p,[1]);marginal(q,[1]);marginal(pq,[1])],c=["red";"green";"black"])

Direct histogram of points from the product

using Gadfly
Pl2 = Gadfly.plot(x=pGM[1,:],y=pGM[2,:],Geom.histogram2d);

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KDE product between non-gaussian distributions

using Distributions
p = kde!(rand(Beta(1.0,0.45),300));
q = kde!(rand(Rayleigh(0.5),100).-0.5);
dummy = kde!(rand(1,100),[1.0]);
pGM, = prodAppxMSGibbsS(dummy, [p;q], nothing, nothing, Niter=5)
pq = kde!(pGM)

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Draw multidimensional distributions as marginalized 2D contour plots

 plot( kde!(randn(4,200)) ) )

pts = [2*randn(1,N).+3;
p, q = kde!(randn(4,100)), kde!(pts);
 plot( [p*q;p;q],c=["red";"black";"blue"], axis=axis, dims=2:4,dimLbls=["w";"x";"y";"z"], levels=4) )

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# or draw product natively
 plot( p*q, axis=axis, dims=[2;4],dimLbls=["w";"x";"y";"z"]) )

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The original C++ kde package was written by Alex Ihler and Mike Mandel in 2003, and has be rewritten in Julia and continuously modified by Dehann Fourie since.

Thank you to contributors and users alike, comments and improvements welcome according to JuliaLang and JuliaRobotics standards.