R/ls.rda.R

In daudi/phutils: Utilities for Public Health Intelligence

##' List the objects in an Rda file.
##' 
##' List the objects in an Rda file. Optionally print the structure of each
##' object.
##' 
##' List the objects in an Rda file.
##' 
##' @param x The path of the Rda file.
##' @param details If TRUE, show summary details of each object, including
##' object name, class, short description and size in Kb.
##' @return A vector with the names of the objects in the file. If details =
##' TRUE then a dataframe with summary details about each object.
##' @author David Whiting, dwhiting@@nhs.net david.whiting@@publichealth.me.uk
##' @keywords utils
##' @examples
##' 
##' ##   x <- ls.rda("example.Rda")
##' 
##' @export
ls.rda <- function(x, details = FALSE) {
  local.ls.rda.y <- local({
    local.ls.rda.y <- load(x)
    
    if (details) {
      this.class <- character(length(local.ls.rda.y))
      desc <- character(length(local.ls.rda.y))
      obj.size <- numeric(length(local.ls.rda.y))
      for (i in 1:length(local.ls.rda.y)) {
        dat <- get(local.ls.rda.y[i])
        this.class[i] <- class(dat)
        
        if (is.list(dat))
          desc[i] <- paste0("list[", length(dat), "]")
        if (is.data.frame(dat))
          desc[i] <- paste0(nrow(dat), " obs. of ", ncol(dat), " variables")
        if (is.matrix(dat))
          desc[i] <- paste(paste(dim(dat), collapse = "x"), "character matrix")
        if (is.function(dat))
          desc[i] <- head(dat, n = 1)    
        
        obj.size[i] <- object.size(dat)
      }
      local.ls.rda.y <- data.frame(object = local.ls.rda.y, 
                                   class = this.class, 
                                   desc = desc,
                                   size_Kb = round(obj.size / 1024, 0))
    }
    local.ls.rda.y
  })
  local.ls.rda.y
}