030_find_replace_patterns.R

#' save_old_names
#' @description safely save copy of original files in separate environmentt
#' @param the_files Unchanged character vector of file names as read from
#' drive.
#' @export
save_old_names <- function(the_files = NULL) {
    e <<- new.env()
    e$the_files <- the_files
}

#'  get_file_names
#'  @description Returns dt, with file names and file size in MB
#'  @param the_dir Directory to find files (DEFAULT= current)
#'  @export
get_file_names <- function(the_dir = ".") {
    # check exists
    the_files <- list.files(path = the_dir, full.names = T)
    ## 1MB = 2^20 (= 1,048,576)
    dt <- data.table(name = the_files, size = file.size(the_files) / 2^20)
}

#'  get_base_name
#'
#'  @description Remove any path information and return base filename and
#'  extension.
#'  @example
#'  # DT[, name := sapply(name, get_base_name)]
#'  @export
## return base name only
get_base_name <- function(e) {
    basename(e)
}


#'  remove_prefix
#'
#' @description Remove any existing prefix according to pattern
#'  May need multiple passes
#' @param files character vector of all possible file names to be changed.
#' @param pattern pattern (or prefix) to remove if found
#' @example
#' # remove_prefix(files=, pattern=)
#' @export
remove_prefix <- function(files = NULL, pattern = NULL) {
    sub(pattern = pattern, replace = "", x = files)
}


#' create_new_prefix
#' @description propose new prefix, min of digits
#' @param the_files character_vector
#' @param digits  sprintf will nice format prefix, padding zeroes to front if
#'  necessary.
#' @export
create_new_prefix <- function(the_files = NULL, digits = 4) {
    n <- length(the_files)
    format <- paste0("%0", digits, "i_")
    the_prefixs <- sprintf(format, 1:n)
}


#' attach_new_prefix
#' @description attach proposed prefix.
#' @param the_files character vector of file names that will receive new prefix.
#' @param prefix Proposed new prefix.
#' @export
attach_new_prefix <- function(the_files = NULL, prefix = NULL) {
    paste0(prefix, the_files)
}