R/object_size.R

In hadley/pryr: Tools for Computing on the Language

#' Compute the size of an object.
#'
#' \code{object_size} works similarly to \code{\link{object.size}}, but counts
#' more accurately and includes the size of environments. \code{compare_size}
#' makes it easy to compare the output of \code{object_size} and
#' \code{object.size}.
#'
#' @section Environments:
#'
#' \code{object_size} attempts to take into account the size of the
#' environments associated with an object. This is particularly important
#' for closures and formulas, since otherwise you may not realise that you've
#' accidentally captured a large object. However, it's easy to over count:
#' you don't want to include the size of every object in every environment
#' leading back to the \code{\link{emptyenv}()}. \code{object_size} takes
#' a heuristic approach: it never counts the size of the global env,
#' the base env, the empty env or any namespace.
#'
#' Additionally, the \code{env} argument allows you to specify another
#' environment at which to stop. This defaults to the environment from which
#' \code{object_size} is called to prevent double-counting of objects created
#' elsewhere.
#'
#' @export
#' @examples
#' # object.size doesn't keep track of shared elements in an object
#' # object_size does
#' x <- 1:1e4
#' z <- list(x, x, x)
#' compare_size(z)
#'
#' # this means that object_size is not transitive
#' object_size(x)
#' object_size(z)
#' object_size(x, z)
#'
#' # object.size doesn't include the size of environments, which makes
#' # it easy to miss objects that are carrying around large environments
#' f <- function() {
#'   x <- 1:1e4
#'   a ~ b
#' }
#' compare_size(f())
#' @param x,... Set of objects to compute total size.
#' @param env Environment in which to terminate search. This defaults to the
#'   current environment so that you don't include the size of objects that
#'   are already stored elsewhere.
#' @return An estimate of the size of the object, in bytes.
object_size <- function(..., env = parent.frame()) {
  lobstr::obj_size(..., env = env)
}

#' @export
#' @rdname object_size
compare_size <- function(x) {
  c(base = utils::object.size(x), pryr = object_size(x))
}