Makie.jl plots

This page shows an example of plotting MCMCChains.jl with Makie.jl. The example is meant to provide an useful basis to build upon. Let's define some random chain and load the required packages:

using MCMCChains

chns = Chains(randn(300, 5, 3), [:A, :B, :C, :D, :E])

Chains MCMC chain (300×5×3 Array{Float64, 3}):

Iterations        = 1:1:300
Number of chains  = 3
Samples per chain = 300
parameters        = A, B, C, D, E

Use `describe(chains)` for summary statistics and quantiles.

A basic way to visualize the chains is to show the drawn samples at each iteration. Colors depict different chains.

using CairoMakie
CairoMakie.activate!(; type="svg")

params = names(chns, :parameters)

n_chains = length(chains(chns))
n_samples = length(chns)

fig = Figure(; resolution=(1_000, 800))

for (i, param) in enumerate(params)
    ax = Axis(fig[i, 1]; ylabel=string(param))
    for chain in 1:n_chains
        values = chns[:, param, chain]
        lines!(ax, 1:n_samples, values; label=string(chain))
    end

    hideydecorations!(ax; label=false)
    if i < length(params)
        hidexdecorations!(ax; grid=false)
    else
        ax.xlabel = "Iteration"
    end
end

fig

Next, we can add a second row of plots next to it which show the density estimate for these samples:

for (i, param) in enumerate(params)
    ax = Axis(fig[i, 2]; ylabel=string(param))
    for chain in 1:n_chains
        values = chns[:, param, chain]
        density!(ax, values; label=string(chain))
    end

    hideydecorations!(ax)
    if i < length(params)
        hidexdecorations!(ax; grid=false)
    else
        ax.xlabel = "Parameter estimate"
    end
end

axes = [only(contents(fig[i, 2])) for i in 1:length(params)]
linkxaxes!(axes...)

fig

Finally, let's add a simple legend. Thanks to setting label above, this legend will have the right labels:

axislegend(first(axes))

fig