environment_name {envnames} | R Documentation |
Retrieve the name of an environment
Description
Retrieve the name of an environment as the environmentName
function of the base package does,
but extending its functionality to retrieving the names of user-defined environments and function
execution environments.
Usage
environment_name(
env = parent.frame(),
envir = NULL,
envmap = NULL,
matchname = FALSE,
ignore = NULL,
include_functions = FALSE
)
Arguments
env |
environment whose name is of interest. It can be given as an object of class environment, as a string with the name of the environment, or as a string with the memory address of the environment. The latter is useful to find out if a given memory address is the reference of an environment object. Note that the variable passed may or may not exist in the calling environment, as the purpose of this function is also to search for it (and return its name if it is an environment). It defaults to parent.frame(), meaning that the name of the environment that calls this function is retrieved. |
envir |
environment where |
envmap |
data frame containing a lookup table with name-address pairs of environment names and
addresses to be used when searching for environment |
matchname |
flag indicating whether the match for |
ignore |
one or more environment names to ignore if found during the search. These environments are removed from the output. It should be given as a character array if more than one environments should be ignored. See the details section for more information. |
include_functions |
flag indicating whether to look for user-defined environments inside function
execution environments. This should be used with care because in a complicated function chain, some function
execution environments may contain environments that point to other environments (e.g. the 'envclos' environment
in the |
Details
If env
is an environment it is searched for in the envir
environment using its memory address.
If env
is a string containing a valid 16-digit memory address (enclosed in < >), the memory address
itself is searched for among the defined environments in the envir
environment.
In both cases, if envir=NULL
the search is carried out in the whole workspace.
It may happen that more than one environment exist with the same memory address (for instance
if an environment is a copy of another environment). In such case, if matchname=FALSE
,
the names of ALL the environments matching env
's memory address are returned. Otherwise,
only the environments matching the given name are returned.
If envmap
is passed it should be a data frame providing an address-name pair lookup table
of environments and should contain at least the following columns:
location
for user-defined environments, the name of the environment where the environment is located; otherwiseNA
.pathname
the full environment path to reach the environment separated by$
(e.g."env1$env$envx"
)address
an 8-digit (32-bit architectures) thru 16-digit (64-bit architectures) memory address of the environment given inpathname
enclosed in < > (e.g."<0000000007DCFB38>"
(64-bit architectures)) Be ware that Linux Debian distributions may have a 12-digit memory address representation. So the best way to know is to check a memory address by calling e.g. 'address("x")'.
Passing an envmap
lookup table is useful for speedup purposes, in case several calls to this
function will be performed in the context of an unchanged set of defined environments.
Such envmap
data frame can be created by calling get_env_names.
Use this parameter with care, as the matrix passed may not correspond to the actual mapping of existing
environments to their addresses and in that case results may be different from those expected.
The following example illustrates the use of the ignore
parameter:
for (e in c(globalenv(), baseenv())) { print(environment_name(e, ignore="e")) }
That is, we iterate on a set of environments and we don't want the loop variable (an environment itself)
to show up as part of the output generated by the call to environment_name()
.
Value
If matchname=FALSE
(the default), an array containing the names of all the environments
(defined in the envir
environment if envir
is not NULL
) having the same memory address
as the env
environment.
If matchname=TRUE
, the environment name contained in env
is used in addition to the memory
address to check the matched environments (potentially many if they have the same memory address)
so that only the environments having the same name and address as the env
environment are returned.
Note that several environments may be found if environments with the same name are defined in
different environments.
WARNING: in this case, the name is matched exactly as the expression given in env
. So for instance,
if env=globalenv()$env1
the name "globalenv()$env1"
is checked and this will not return any
environments since no environment can be called like that. For such scenario call the function with
parameter env=env1
instead, or optionally with env=env1
and envir=globalenv()
if the env1
environment should be searched for just in the global environment.
If env
is not found or it is not an environment, NULL
is returned.
Examples
# Retrieve name of a user-defined environment
env1 <- new.env()
environment_name(env1) # "env1"
# Retrieve the name of an environment given as a memory address
env1_address = get_obj_address(globalenv()$env1)
environment_name(env1_address) # "env1"
# Create a copy of the above environment
env1_copy <- env1
environment_name(env1) # "env1" "env1_copy"
# Retrieve just the env1 environment name
environment_name(env1, matchname=TRUE) # "env1"
# Retrieve the name of an environment defined within another environment
with(env1, envx <- new.env())
environment_name(env1$envx) # "env1$envx" "env1_copy$envx"
environment_name(env1$envx, matchname=TRUE)
## NULL, because the environment name is "envx", NOT "env1$envx"
# Get a function's execution environment name
with(env1, f <- function() { cat("We are inside function", environment_name()) })
## "We are inside function env1$f"