ls
List Objects
ls and objects return a vector of character strings
giving the names of the objects in the specified environment. When
invoked with no argument at the top level prompt, ls shows what
data sets and functions a user has defined. When invoked with no
argument inside a function, ls returns the names of the
function's local variables: this is useful in conjunction with
browser.
- Keywords
- environment
Usage
ls(name, pos = -1L, envir = as.environment(pos), all.names = FALSE, pattern)
objects(name, pos= -1L, envir = as.environment(pos), all.names = FALSE, pattern)Arguments
- name
- which environment to use in listing the available objects.
Defaults to the current environment. Although called
namefor back compatibility, in fact this argument can specify the environment in any form; see the ‘Details’ section. - pos
- an alternative argument to
namefor specifying the environment as a position in the search list. Mostly there for back compatibility. - envir
- an alternative argument to
namefor specifying the environment. Mostly there for back compatibility. - all.names
- a logical value. If
TRUE, all object names are returned. IfFALSE, names which begin with a . are omitted. - pattern
- an optional regular expression. Only names
matching
patternare returned.glob2rxcan be used to convert wildcard patterns to regular expressions.
Details
The name argument can specify the environment from which
object names are taken in one of several forms:
as an integer (the position in the search list); as
the character string name of an element in the search list; or as an
explicit environment (including using
sys.frame to access the currently active function calls).
By default, the environment of the call to ls or objects
is used. The pos and envir arguments are an alternative
way to specify an environment, but are primarily there for back
compatibility.
Note that the order of the resulting strings is locale
dependent, see Sys.getlocale.
References
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.
See Also
glob2rx for converting wildcard patterns to regular
expressions.
ls.str for a long listing based on str.
apropos (or find)
for finding objects in the whole search path;
grep for more details on ‘regular expressions’;
class, methods, etc., for
object-oriented programming.
Examples
library(base)
.Ob <- 1
ls(pattern = "O")
ls(pattern= "O", all.names = TRUE) # also shows ".[foo]"
# shows an empty list because inside myfunc no variables are defined
myfunc <- function() {ls()}
myfunc()
# define a local variable inside myfunc
myfunc <- function() {y <- 1; ls()}
myfunc() # shows "y"