R/formant_to_df.R

In phonfieldwork: Linguistic Phonetic Fieldwork Tools

#' Praat Formant object to dataframe
#'
#' Convert a Praat Formant object to a dataframe.
#'
#' @author George Moroz <agricolamz@gmail.com>
#'
#' @param file_name string with a filename or path to the Formant file
#'
#' @return a dataframe with columns:  \code{time_start}, \code{time_end},
#' \code{frequency}, \code{bandwidth} and \code{formant}
#'
#' @examples
#' formant_to_df(system.file("extdata", "e.Formant", package = "phonfieldwork"))
#' @export
#'
#' @importFrom uchardet detect_file_enc
#'

formant_to_df <- function(file_name) {
  # read file ---------------------------------------------------------------
  if (grepl("Formant", file_name[2])) {
    formant <- file_name
  } else {
    # thanks to Artem Klevtsov for this code
    con <- file(file_name, encoding = uchardet::detect_file_enc(file_name))
    formant <- readLines(con)
    close(con)
  }

  # get metadata ------------------------------------------------------------
  time_start <- as.numeric(gsub("[^0-9\\.]", "", formant[grep("xmin =", formant)]))
  time_end <- as.numeric(gsub("[^0-9\\.]", "", formant[grep("xmax =", formant)]))

  # get all frames ----------------------------------------------------------
  s <- split(seq_along(formant), cumsum(grepl("frames \\[\\d{1,}\\]", formant)))
  s <- s[-1]
  result <- lapply(seq_along(s), function(i) {
    data.frame(
      id = i,
      formant = 1:sum(grepl("frequency =", formant[s[[i]]])),
      frequency = grep("frequency =", formant[s[[i]]], value = TRUE),
      bandwidth = grep("bandwidth =", formant[s[[i]]], value = TRUE)
    )
  })

  result <- do.call(rbind, result)
  result$frequency <- as.numeric(gsub("[^0-9\\.]", "", result$frequency))
  result$bandwidth <- as.numeric(gsub("[^0-9\\.]", "", result$bandwidth))

  df <- data.frame(
    id = seq_along(s),
    time_start = seq(time_start, time_end,
      length.out = length(s)
    )
  )
  result <- merge(result, df, by = "id")
  result$time_end <- result$time_start
  return(result[, -1])
}