DEMAP {DEBBI} R Documentation

## DEMAP

### Description

DE optimization for maximum a posteriori (MAP) estimation; his function tries to find the posterior mode.

### Usage

DEMAP(LogPostLike, control_params = AlgoParamsDEMAP(), ...)


### Arguments

 LogPostLike function whose first argument is an n_params-dimensional model parameter vector and returns (scalar) sum of log prior density and log likelihood for the parameter vector. control_params control parameters for DE algorithm. see AlgoParamsDEMAP function documentation for more details. ... additional arguments to pass LogPostLike

### Value

list contain posterior samples from DEMCMC in a n_iters_per_chain by n_chains by n_params array and the log likelihood of each sample in a n_iters_per_chain by n_chains array.

### Examples

# simulate from model
dataExample <- matrix(stats::rnorm(100, c(-1, 1), c(1, 1)), nrow = 50, ncol = 2, byrow = TRUE)

# list parameter names
param_names_example <- c("mu_1", "mu_2")

# log posterior likelihood function = log likelihood + log prior | returns a scalar
LogPostLikeExample <- function(x, data, param_names) {
out <- 0

names(x) <- param_names

# log prior
out <- out + sum(dnorm(x["mu_1"], 0, sd = 1, log = TRUE))
out <- out + sum(dnorm(x["mu_2"], 0, sd = 1, log = TRUE))

# log likelihoods
out <- out + sum(dnorm(data[, 1], x["mu_1"], sd = 1, log = TRUE))
out <- out + sum(dnorm(data[, 2], x["mu_2"], sd = 1, log = TRUE))

return(out)
}

# Get map estimates
DEMAP(
LogPostLike = LogPostLikeExample,
control_params = AlgoParamsDEMAP(
n_params = length(param_names_example),
n_iter = 1000,
n_chains = 12
),
data = dataExample,
param_names = param_names_example
)



[Package DEBBI version 0.1.0 Index]