R: Gets a variable by name

eget {R.utils} | R Documentation

## Gets a variable by name

### Description

Gets a variable by name. If non-existing, the default value is returned.

### Usage

    eget(..., coerce=TRUE, envir=parent.frame(), inherits=FALSE, mode="default",
      cmdArg=FALSE)

### Arguments

`...` | Named arguments `name` and `default`, where `name` must be a `character` string and `default` is an optional default value (if not given, it's `NULL`). Alternatively, `name` and `default` can be given as a named argument (e.g. `n=42`).
`coerce` | If `TRUE`, the returned value is coerced to the class of the default value (unless `NULL`) using `as`.
`envir` | A `environment` or a named `list` where to look for the variable. Only if `envir` is an `environment`.
`inherits` | A `logical` specifying whether the enclosing frames of the environment should be searched or not.
`mode` | A `character` string specifying the mode of the object to retrieve. Only if `envir` is an `environment`.
`cmdArg` | If `TRUE`, the corresponding command-line argument is used as the default value.

### Details

`ecget(...)` is short for `eget(..., cmdArg=TRUE)`.

### Value

Returns an object.

### Author(s)

Henrik Bengtsson

### See Also

To retrieve command-line arguments, see `cmdArg`. See also `mget`().

### Examples

    # Get variable 'a' if it exists, otherwise return the default value.
    value <- eget("a", default=42L)
    print(value) # 42L

    # Short version doing the same
    value <- eget(a=42L)
    print(value) # 42L

    # Same, but look for the variable in 'envir' (here a list)
    value <- eget("a", default=42L, envir=list(a=1))
    print(value) # 1L

    # Get variable 'n', which defaults to command-line argument
    # 'n' ('-n' or '--n'), which in turn defaults to 42L.
    value <- eget(n=cmdArg(n=42L))
    print(value)

    # Equivalently.
    value <- ecget(n=42L)
    print(value)

[Package R.utils version 2.7.0 Index]