obj_size: Calculate the size of an object.

In lobstr: Visualize R Data Structures with Trees

Calculate the size of an object.

Description

obj_size() computes the size of an object or set of objects; obj_sizes() breaks down the individual contribution of multiple objects to the total size.

Usage

obj_size(..., env = parent.frame())

obj_sizes(..., env = parent.frame())

Arguments

...	Set of objects to compute size.
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. Regardless of the value here, obj_size() never looks past the global or base environments.

Value

An estimate of the size of the object, in bytes.

Compared to object.size()

Compared to object.size(), obj_size():

• Accounts for all types of shared values, not just strings in the global string pool.

• Includes the size of environments (up to env)

• Accurately measures the size of ALTREP objects.

Environments

obj_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 emptyenv(). obj_size() takes a heuristic approach: it never counts the size of the global environment, the base environment, the empty environment, or any namespace.

Additionally, the env argument allows you to specify another environment at which to stop. This defaults to the environment from which obj_size() is called to prevent double-counting of objects created elsewhere.

Examples

# obj_size correctly accounts for shared references
x <- runif(1e4)
obj_size(x)

z <- list(a = x, b = x, c = x)
obj_size(z)

# this means that object size is not transitive
obj_size(x)
obj_size(z)
obj_size(x, z)

# use obj_size() to see the unique contribution of each component
obj_sizes(x, z)
obj_sizes(z, x)
obj_sizes(!!!z)

# obj_size() also includes the size of environments
f <- function() {
  x <- 1:1e4
  a ~ b
}
obj_size(f())

#' # In R 3.5 and greater, `:` creates a special "ALTREP" object that only
# stores the first and last elements. This will make some vectors much
# smaller than you'd otherwise expect
obj_size(1:1e6)

lobstr documentation built on June 23, 2022, 1:05 a.m.