R/csv2struct.R

In tagtools: Work with Data from High-Resolution Biologging Tags

#' Read tag metadata from csv
#'
#' Read a CSV metadata file and convert it into a metadata list.
#' A metadata file is a comma-separated text file (.csv) containing a line for each metadata
#' entry. The first comma-separated field in each line is the name of the
#' entry. The last field in each line contains the value to
#' be assigned to this metadata entry. The value can be a string or number
#' but is always saved as a string in the structure - it is up to downstream
#' users of the metadata to parse/decode the entries.
#' 
#' @param fname Name of the text file to be read. If no file extension is provided, '.csv' will be
#' added automatically. If the file is not located in the current working directory, then \code{fname} must include the correct relative or absolute path.
#' @return a metadata list populated from \code{fname} (one list element per row in the file). All list elements are stored as \code{"character"} class objects (even if the field contains a number, a date, etc) - no attempt is made to determine the most appropriate class for each item.
#' @export
#' @examples
#' hold <- system.file("extdata","metadata_example.csv", package = "tagtools", mustWork = TRUE)
#' S <- csv2struct(hold)
#'
csv2struct <- function(fname) {
  if (missing(fname)) {
    stop('Please provide a file name for csv2struct')
  }
  
  if (!grepl('.csv', fname)) {
    fname <- paste(fname, '.csv', sep='')
  }
  
  S0 <- utils::read.csv(file = fname, colClasses = c(params = "character"))
  S <- as.list(S0$params)
  names(S) <- gsub(pattern = '.', replacement = '_', S0$field, fixed = TRUE)
  
  return(S)
}