R/getFileExt.R

In IFC: Tools for Imaging Flow Cytometry

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# This file is released under the GNU General Public License, Version 3, GPL-3 #
# Copyright (C) 2020 Yohann Demont                                             #
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# It is part of IFC package, please cite:                                      #
# -IFC: An R Package for Imaging Flow Cytometry                                #
# -YEAR: 2020                                                                  #
# -COPYRIGHT HOLDERS: Yohann Demont, Gautier Stoll, Guido Kroemer,             #
#                     Jean-Pierre Marolleau, Loïc Garçon,                      #
#                     INSERM, UPD, CHU Amiens                                  #
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#' @title File Extension Retrieval
#' @description 
#' Determines extension from alpha numeric file name.
#' @param x path to file.
#' @source derived from file_ext() in \pkg{tools}, R Core Team, Kurt Hornik and Friedrich Leisch.
#' @return the file extension in lower case if found. Otherwise, "".
#' @keywords internal
getFileExt <- function (x) {
  pos <- regexpr("\\.([[:alnum:]]+)$", x)
  tolower(ifelse(pos > -1L, substring(x, pos + 1L), ""))
}