R/verifyFileList.R

In mikemeredith/saveJAGS: Run JAGS and Regularly Save Output to Files

# Function to check a fileList object and extract key values

verifyFileList <- function(fileList) {
  if(!dir.exists(dirname(fileList[[1]][1])))
    stop("Can't find the folder: ", dirname(fileList[[1]][1]), call. = FALSE)
  if(!file.exists(fileList[[1]][1]))
    stop("Can't find the first file: ", fileList[[1]][1], call. = FALSE)

  # Open first file and check stuff
  loadEnv <- new.env(FALSE)  # Need to ring-fence the stuff loaded
  chk <- load(fileList[[1]][1], envir=loadEnv)
  if(!("out" %in% chk) || is.null(loadEnv$out) ||
          class(loadEnv$out) != "mcmc.list")
    stop("fileList is not a valid saveJAGS file list", call. = FALSE)
  if(length(loadEnv$out) != 1)
    stop("Files should contain a single chain.", call. = FALSE)

  # Get items to return
  nodes <- colnames(loadEnv$out[[1]])
  base <- sapply(strsplit(nodes, "\\["), "[", 1)
  out <- list(
    niter = nrow(loadEnv$out[[1]]),
    nthin = coda::thin(loadEnv$out),
    nodes = nodes,
    base = base,
    parNames = unique(base) )
  return(out)
}