R/leading_zero.R

In vmikk/metagMisc: Miscellaneous functions for metagenomic analysis

#' @title Add or remove leading zeros
#'
#' @param x Numeric or character vector
#' @param z Number of significant digits of the resulting number with leading zeros (if NULL, it will be detected automatically)
#' @param mode "add" or "remove" leading zero
#'
#' @details 
#' In 'add' mode, the function adds leading zeros to the numbers to make them all the same length.  
#' In 'remove' mode, the function removes leading zeros. 
#' The pattern used for removing leading zeros removes all zeros that are either at the beginning of the string
#' (e.g., '0001' -> '1') or following non-digit characters (e.g., 'sample001' -> 'sample1').
#'
#' @return A vector with (mode = "add) or without (mode = "remove") leading zeros
#' @export
#'
#' @examples
#' leading_zero(1:10, z=3)
#' leading_zero(c(1,10,100,1000,10000))
#' leading_zero(c("001", "1001", "g01", "0abc"), mode = "remove")
#' leading_zero(x = "sample001", mode = "remove")  # sample1
#'
leading_zero <- function(x, z = NULL, mode = "add"){

  ## Add leading zeros
  if(mode == "add"){
    if(is.null(z)){
      ## Find the number of characters
      z <- nchar(as.integer(max(x)))
    }

    zz <- paste("%0", z, "d", sep = "")
    res <- sprintf(zz, x)
  }

  ## Remove leading zeros
  if(mode == "remove"){
    res <- gsub("(^|[^0-9])0+", "\\1", x, perl = TRUE)
  }

  return(res)
}