R/loadFile.R

In ribiosIO: Input/Output Utilities of the 'ribios' Suite

#' Attempt to load a binary RData file
#' 
#' The function attempts to load a binary file, returning \code{TRUE} if
#' succeeded. Otherwise it returns \code{FALSE}.
#' 
#' 
#' @param rDataFile Character, RData file name
#' @param env Environment, where should be the RData loaded into. By default it
#' is loaded into the caller's environment.
#' @return Logical, \code{TRUE} if the file was loaded successfully,
#' \code{FALSE} otherwise.
#' @author Jitao David Zhang <jitao_david.zhang@@roche.com>
#' @seealso \code{\link{iofile}} can be used to find file from input data
#' directory.
#' @examples
#' rf <- tempfile()
#' myData <- c(3,4,5)
#' save(myData, file=rf)
#' env <- new.env()
#' stopifnot(loadFile(rf, env=env))
#'
#' @export loadFile
loadFile <- function (rDataFile, env = parent.frame()) {
    if (file.exists(rDataFile)) {
        load(rDataFile, env)
        return(TRUE)
    }
    else {
        return(FALSE)
    }
}

#' Load an object by its name from a RData file
#' @param file A RData file
#' @param obj Object name. If set as \code{NULL}, all objects are returned
#' @param verbose Whether the loading process should be verbose, see \code{\link{load}}
#'
#' @return The object loaded from the RData file. If \code{obj} is \code{NULL},
#' returns the first object found.
#' @export
loadObject <- function(file, obj=NULL, verbose=FALSE) {
  env <- new.env()
  load(file, env, verbose = verbose)
  if(is.null(obj))
     obj <- ls(envir=env)
  get(obj, env)
}


#' Load objects from a RData file and return them in an environment
#' @param file A RData file
#' @param obj Character string(s), optional object names. If set as \code{NULL}, all objects are returned
#' @param verbose Whether the loading process should be verbose, see \code{\link{load}}
#'
#' @return An environment containing the loaded objects.
#' @export
loadObjectInEnv <- function(file, obj=NULL, verbose=FALSE) {
  env <- new.env()
  load(file, env, verbose = verbose)
  if(!is.null(obj)) {
    eobj <- ls(envir=env)
    fobj <- intersect(obj, eobj)
    nfobj <- setdiff(obj, eobj)
    if(length(nfobj)>0)
        warning("Following objects not found:", paste(nfobj, collapse=","))
    rm(list=nfobj, envir=env)
  }
  return(env)
}


#' Load an object from a RDS file and returns a logical flag
#' 
#' @param rdsFile Character string, name of the rds file to be loaded
#' @param variableName Character string or variable name, variable name to which the loaded value is assigned to
#' @param refhook Logical, passed to \code{\link[base]{readRDS}}
#' 
#' @return Logical, \code{TRUE} if the file loading was successful, otherwise \code{FALSE}
#' @export
loadRDS <- function(rdsFile, variableName, refhook=NULL) {
  variableName <- as.character(substitute(variableName))
  if(file.exists(rdsFile)) {
    obj <- readRDS(rdsFile, refhook=refhook)
    assign(variableName, value=obj, envir=parent.frame())
    return(TRUE)
  } else {
    return(FALSE)
  }
}