Get, set, test for and create environments.
environment(fun = NULL) environment(fun) <- value is.environment(x) .GlobalEnv globalenv() .BaseNamespaceEnv emptyenv() baseenv() new.env(hash = TRUE, parent = parent.frame(), size = 29L) parent.env(env) parent.env(env) <- value environmentName(env) env.profile(env)
NULL, which is the default.
- an environment to associate with the function
- an arbitrary R object.
- a logical, if
TRUEthe environment will use a hash table.
- an environment to be used as the enclosure of the environment created.
- an environment
- an integer specifying the initial size for a hashed environment. An internal default value will be used if
NAor zero. This argument is ignored if
Environments consist of a frame, or collection of named objects, and a pointer to an enclosing environment. The most common example is the frame of variables local to a function call; its enclosure is the environment where the function was defined (unless changed subsequently). The enclosing environment is distinguished from the parent frame: the latter (returned by
parent.frame) refers to the environment of the caller of a function. Since confusion is so easy, it is best never to use ‘parent’ in connection with an environment (despite the presence of the function
The global environment
.GlobalEnv, more often known as the user's workspace, is the first item on the search path. It can also be accessed by
globalenv(). On the search path, each item's enclosure is the next item.
The replacement function
parent.env<- is extremely dangerous as it can be used to destructively change environments in ways that violate assumptions made by the internal C code. It may be removed in the near future.
System environments, such as the base, global and empty environments, have names as do the package and namespace environments and those generated by
attach(). Other environments can be named by giving a
"name" attribute, but this needs to be done with care as environments have unusual copying semantics.
fun is a function or a formula then
environment(fun) returns the environment associated with that function or formula. If
NULL then the current evaluation environment is returned.
The replacement form sets the environment of the function or formula
fun to the
new.env returns a new (empty) environment with (by default) enclosure the parent frame.
parent.env returns the enclosing environment of its argument.
parent.env<- sets the enclosing environment of its first argument.
environmentName returns a character string, that given when the environment is printed or
"" if it is not a named environment.
env.profile returns a list with the following components:
size the number of chains that can be stored in the hash table,
nchains the number of non-empty chains in the table (as reported by
counts an integer vector giving the length of each chain (zero for empty chains). This function is intended to assess the performance of hashed environments. When
env is a non-hashed environment,
NULL is returned.
For the performance implications of hashing or not, see http://en.wikipedia.org/wiki/Hash_table.
sys.source can be used to populate an environment.
f <- function() "top level function" ##-- all three give the same: environment() environment(f) .GlobalEnv ls(envir = environment(stats::approxfun(1:2, 1:2, method = "const"))) is.environment(.GlobalEnv) # TRUE e1 <- new.env(parent = baseenv()) # this one has enclosure package:base. e2 <- new.env(parent = e1) assign("a", 3, envir = e1) ls(e1) ls(e2) exists("a", envir = e2) # this succeeds by inheritance exists("a", envir = e2, inherits = FALSE) exists("+", envir = e2) # this succeeds by inheritance eh <- new.env(hash = TRUE, size = NA) with(env.profile(eh), stopifnot(size == length(counts)))
Documentation reproduced from R 3.0.2. License: GPL-2.