hack to parse a list of initial values for use in greta

initial_values_hack.R

to_free <- function (node, data) {
  lower <- node$lower
  upper <- node$upper
  fun <- switch(node$constraint,
                none = function (x) x,
                high = function (x) log(x - lower),
                low = function (x) log(upper - x),
                both = function(x) qlogis((y - lower) / (upper - lower)))
  fun(data)
}

parse_inits <- function (inits, model) {
  
  # line up greta array names with tf names
  unlist_tf <- greta::.internals$utils$samplers$unlist_tf
  greta_names <- names(model$dag$parameters_example)
  tf_names <- vapply(names(inits),
                     function(name) model$dag$tf_name(get(name)$node),
                     "")
  order <- match(greta_names, tf_names)
  
  # reorder the inits, and transform them to the free scale
  inits <- inits[order]
  
  inits <- lapply(inits, as.array)
  
  nodes <- model$dag$node_list[match(tf_names, model$dag$node_tf_names)]
  inits <- mapply(to_free, nodes, inits)

  unlist_tf(inits)
  
}