Takes output from Stan Optimizing and cleans it to more standard form.

Clean Optimizing Output from Rstan

#' Clean Output of Stan Optimizing Samples
#'
#' @param optimfit result of call to rstan::optimizing
#' @param pars optional character vector of parameters to include
#'
#' @return list of arrays
#' @importFrom stringr str_count
#' @importFrom rlang syms
#' @importFrom dplyr matches select mutate
#' @importFrom tidyr gather separate
#' @importFrom purrr map map2
#' @importFrom driver spread_array
#' @export
clean_optimizing <- function(draws, pars=NULL){
  cl <- draws %>%
    as.data.frame()
  if (!is.null(pars)) cl <- select(cl, dplyr::matches(paste0("^(",paste(pars, collapse = "|"), ")\\["), ignore.case=FALSE))
  cl <- cl %>%
    mutate(dim_1 = 1:n()) %>%
    gather(par, val, -dim_1) %>%
    separate(par, c("parameter", "dimensions"), sep="\\[|\\]", extra="drop") %>%
    split(., .$parameter)
  dn <- map(cl, ~str_count(.x$dimensions[1], "\\,")+1) %>%
    map(~paste0("dim", 1:.x))
  cl <- cl %>%
    map2(dn, ~separate(.x, dimensions, .y, "\\,", convert=TRUE)) %>%
    map(~dplyr::select(.x, -parameter)) %>%
    map2(dn, ~spread_array(.x, val, !!!rlang::syms(c("dim_1", .y))))
  return(cl)
}