R: List Objects

ls {base} | R Documentation

## List Objects

### Description

`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`.

### 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 `name` for back compatibility, in fact this argument can specify the environment in any form; see the ‘Details’ section.
`pos` | an alternative argument to `name` for specifying the environment as a position in the search list. Mostly there for back compatibility.
`envir` | an alternative argument to `name` for specifying the environment. Mostly there for back compatibility.
`all.names` | a logical value. If `TRUE`, all object names are returned. If `FALSE`, names which begin with a . are omitted.
`pattern` | an optional regular expression. Only names matching `pattern` are returned. `glob2rx` can 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

    .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"

[Package base version 3.1.2 Index]