R/keep.R

In flor3652/myStuff: My Stuff

#' @title The Keep Function
#' 
#' @description
#' This function is designed to keep a given list of variables (as opposed to the rm function, which is designed to remove a list of variables)
#' 
#' @param ... Variables that should stay in the environment
#' @param x A character vector of variables which you wish to keep
#' 
#' @details
#' The function uses the \code{ls} command to find the variables that are defined in the parent environment. It then deletes all variables that are not given as an argument.
#' 
#' @author Michael Floren
#' 
#  For whatever reason, I CANNOT get this link to the "rm" function to actually create a hyperlink
#' @seealso \code{\link[base]{rm}}
#' 
keep <- function(..., x = c())
{
  
  if (length(x) > 0)
  {
    if (!is.character(x)) 
      stop("x must contain character vector")
    
    L <- ls(name = parent.frame())
    rm(list = L[!L %in% x], pos = parent.frame())
    
    return(invisible(ls(name = parent.frame())))
  }
  
  dots <- match.call(expand.dots = FALSE)$...
  
  if (length(dots) && !all(sapply(dots, function(x) is.symbol(x) || 
                                  is.character(x)))) 
    stop("... must contain names or character strings")
  
  names <- sapply(dots, as.character)
  L <- ls(name = parent.frame())
  rm(list = L[!L %in% names], pos = parent.frame())
  
  return(invisible(ls(name = parent.frame())))
  
}