Printing loglikelihood values

New to Julia
,
1

Can we print likelihood values while sampling by NUTS() in turing.jl? Is there any way ? So, we don’t sit blind during run and have some info.

2

Do something like the following:

using Distributions, Turing, StatsPlots
function main(n)
# sample is from exponential, prior is lognormal
y = rand(Exponential(3.0), n)
# the model: prior and likelihood
@model function ExpModel(y)
    θ ~ LogNormal(1.,1.) # the prior
    y ~ Exponential(θ)   # the likelihood
    @show loglikelihood(Exponential(θ), y)
end    
# get the chain
chain = sample(ExpModel(y), NUTS(200, 0.65), 1000)
end

## run it
n = 300
chain = main(n)

## examine and plot last bit of chain chain
display(chain)
plot(chain[end-500:end])

I just explained this example in class earlier today, so I had it in mind! The line with @show is what displays the loglikelihood. Doing that might slow things down, I haven’t checked.

3

Thank you for your reply and example :slight_smile:

It shows loglikelihood but its more like just printing everything. I was looking for something which be more like updating loglikelihood lets say after every x = 100 . So, for your example it should only print 3 times for n=300

4

I suppose that would require modifying sample from Turing. It might be a nice issue to raise, I can see it being useful for long running samples that might be straying into problems.

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