Reorder MCMC Start Values to Match Prior Specification

Ensures that the rows of a matrix of MCMC start values are ordered consistently with the names in the param_priors list. This is useful when passing initial values to an MCMC routine that expects a specific parameter order.

Usage

reorder_start_values(start_values, param_priors)

Arguments

start_values

A matrix of initial parameter values for MCMC, where each row corresponds to a parameter and each column to a chain or initialization. The row names should be the parameter names.

param_priors

A named list of prior specifications (e.g., as used by mcstate::pmcmc_parameters$new()), where names correspond to parameter names.

Value

A reordered matrix of start values with the row order matching the order of names in param_priors. Parameters missing from start_values are dropped (with a warning optionally).

Details

The function matches parameter names from start_values to those in param_priors, and reorders them accordingly. Any parameters present in param_priors but missing in start_values are ignored in the returned matrix.

Examples

start_vals <- matrix(c(0.1, 0.2, 0.3, 0.4), nrow = 2, dimnames = list(c("beta", "gamma"), NULL))
priors <- list(gamma = list(min = 0, max = 1, prior = dunif),
               beta = list(min = 0, max = 1, prior = dunif))
reordered <- reorder_start_values(start_vals, priors)