inst/examples/createPrior.R

# Create a general prior distribution by specifying an arbitrary density function and a
# corresponding sampling function
density = function(par){
  d1 = dunif(par[1], -2,6, log =TRUE)
  d2 = dnorm(par[2], mean= 2, sd = 3, log =TRUE)
  return(d1 + d2)
}

# The sampling is optional but recommended because the MCMCs can generate automatic starting
# conditions if this is provided
sampler = function(n=1){
  d1 = runif(n, -2,6)
  d2 = rnorm(n, mean= 2, sd = 3)
  return(cbind(d1,d2))
}

prior <- createPrior(density = density, sampler = sampler, 
                     lower = c(-3,-3), upper = c(3,3), best = NULL)


# Use this prior in an MCMC 

ll <- function(x) sum(dnorm(x, log = TRUE)) # multivariate normal ll
bayesianSetup <- createBayesianSetup(likelihood = ll, prior = prior)

settings = list(iterations = 1000)
out <- runMCMC(bayesianSetup = bayesianSetup, settings = settings)

# see ?createPriorDensity for how to create a new prior from this output

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BayesianTools documentation built on Dec. 10, 2019, 1:08 a.m.