Dirichlet Nucleotide Frequency Prior applet

The Dirichlet distribution is normally used to specify the prior distribution for equilibrium base frequencies in Bayesian phylogenetics. Unfortunately, 4 dimensions are required to plot the probability density, so I’ve resorted to showing you samples from the distribution instead plotted using a barycentric coordinate system.

Drag right-to-left (or left-to-right) with mouse to rotate view. Use controls below plot to change sampling distribution. Relative distance from vertex A, for example, is proportional to nucleotide frequency of A.


This applet makes use of d3js and Erik Bernhardsson’s very useful D3-3D code. Please see the GitHub site for details about licensing of other libraries that may have been used in the source code for this applet.


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