| environment {base} | R Documentation |
Get, set, test for and create environments.
environment(fun = NULL) environment(fun) <- value is.environment(x) .GlobalEnv globalenv() .BaseNamespaceEnv emptyenv() baseenv() new.env(hash = FALSE, parent = parent.frame(), size = 29L) parent.env(env) parent.env(env) <- value environmentName(env) env.profile(env)
fun |
a function, a formula, or
NULL, which is the default. |
value |
an environment to associate with the function |
x |
an arbitrary R object. |
hash |
a logical, if TRUE the environment will be hashed |
parent |
an environment to be used as the enclosure of the environment created. |
env |
an environment |
size |
an integer specifying the initial size for a hashed
environment. An internal default value will be used if
size is NA or zero. This argument is ignored if
hash is FALSE. |
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. 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.
When get or exists search an environment
with the default inherits = TRUE, they look for the variable
in the frame, then in the enclosing frame, and so on.
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 object .BaseNamespaceEnv is the name space environment for
the base package. The environment of the base package itself is
available as baseenv(). The ultimate enclosure of any environment
is the empty environment emptyenv(), to which nothing may
be assigned.
If one follows the parent.env() chain of enclosures back far
enough from any environment, eventually one reaches the empty
environment.
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.
If fun is a function or a formula then environment(fun)
returns the environment associated with that function or formula.
If fun is NULL then the current evaluation environment is
returned.
The replacement form sets the environment of the function or formula
fun to the value given.
is.environment(obj) returns TRUE if and only if
obj is anenvironment.
new.env returns a new (empty) environment enclosed in the
parent's environment, by default.
parent.env returns the parent 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 HASHPRI),
and 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.
The envir argument of eval, get,
and exists.
ls may be used to view the objects in an environment,
and hence ls.str may be useful for an overview.
sys.source can be used to “fill” an environment.
f <- function() "top level function"
##-- all three give the same:
environment()
environment(f)
.GlobalEnv
ls(envir=environment(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, env=e1)
ls(e1)
ls(e2)
exists("a", env=e2) # this succeeds by inheritance
exists("a", env=e2, inherits = FALSE)
exists("+", env=e2) # this succeeds by inheritance