R: Simple access to parsed command-line arguments

cmdArgs {R.utils} | R Documentation

## Simple access to parsed command-line arguments

### Description

Simple access to parsed command-line arguments.

### Usage

      cmdArgs(args=NULL, names=NULL, unique=TRUE, ..., .args=NULL)
      cmdArg(...)

### Arguments

`args` | A named `list` of arguments.
`names` | A `character` `vector` specifying the arguments to be returned. If `NULL`, all arguments are returned.
`unique` | If `TRUE`, only unique arguments are returned.
`...` | For `cmdArgs()`, additional arguments passed to `commandArgs`(), e.g. `defaults` and `always`. For `cmdArg()`, 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`).
`.args` | (advanced/internal) A named `list` of parsed command-line arguments.

### Value

`cmdArgs()` returns a named `list` with command-line arguments. `cmdArg()` return the value of the requested command-line argument.

### Coercing to non-character data types

The value of each command-line argument is returned as a `character` string, unless an argument share name with ditto in the (optional) arguments `always` and `default` in case the retrieved value is coerced to that of the latter. Finally, remaining character string command-line arguments are coerced to `numeric`s (via `as.numeric`()), if possible, that is unless the coerced value becomes `NA`.

### Author(s)

Henrik Bengtsson

### See Also

Internally, `commandArgs`() is used.

### Examples

    args <- cmdArgs()
    cat("User command-line arguments used when invoking R:\n")
    str(args)

    # Retrieve command line argument 'n', e.g. '-n 13' or '--n=13'
    n <- cmdArg("n", 42L)
    printf("Argument n=%d\n", n)

    # Short version doing the same
    n <- cmdArg(n=42L)
    printf("Argument n=%d\n", n)

[Package R.utils version 2.7.0 Index]