cmdArgs: 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 numerics (via as.numeric()), if possible, that is unless the coerced value becomes NA.

Examples

Run this code

# NOT RUN {
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)

# }