Get, set, test for and create environments.
environment(fun = NULL) environment(fun) <- valueis.environment(x).GlobalEnv globalenv() .BaseNamespaceEnvemptyenv() baseenv()new.env(hash = TRUE, parent = parent.frame(), size = 29L)parent.env(env) parent.env(env) <- valueenvironmentName(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.
.BaseNamespaceEnv is the namespace environment for
the base package. The environment of the base package itself is
If one follows the chain of enclosures found by repeatedly calling
parent.env from any environment, eventually one reaches the
emptyenv(), into which nothing may
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.
The replacement form of
System environments, such as the base, global and empty environments,
have names as do the package and namespace environments and those
attach(). Other environments can be named by
"name" attribute, but this needs to be done with care
as environments have unusual copying semantics.
funis a function or a formula then
environment(fun)returns the environment associated with that function or formula. If
NULLthen the current evaluation environment is returned.The replacement form sets the environment of the function or formula
TRUEif and only if
new.envreturns a new (empty) environment with (by default) enclosure the parent frame.
parent.envreturns the enclosing environment of its argument.
parent.env<-sets the enclosing environment of its first argument.
environmentNamereturns a character string, that given when the environment is printed or
""if it is not a named environment.
env.profilereturns a list with the following components:
sizethe number of chains that can be stored in the hash table,
nchainsthe number of non-empty chains in the table (as reported by
countsan integer vector giving the length of each chain (zero for empty chains). This function is intended to assess the performance of hashed environments. When
envis a non-hashed environment,
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)))