Create a command line parser

ArgumentParser() creates a parser object that acts as a wrapper to Python's argparse module

Usage

ArgumentParser(..., python_cmd = NULL)

Arguments

...

Arguments cleaned and passed to Pythons argparse.ArgumentParser()

python_cmd

Python executable for argparse to use. Must have argparse and json modules (automatically bundled with Python 2.7 and 3.2+). If you need Unicode argument support then you must use Python 3.0+. Default will be to use findpython package to find suitable Python binary.

Value

ArgumentParser() returns a parser object which contains an add_argument() function to add arguments to the parser, a parse_args() function to parse command line arguments into a list, a print_help() and a print_usage() function to print usage information. See code examples, package vignette, and corresponding python module for more information on how to use it.

References

Python's argparse library, which this package is based on, is described here: https://docs.python.org/3/library/argparse.html

Examples

if (argparse:::detects_python()) {
  parser <- ArgumentParser(description='Process some integers')
  parser$add_argument('integers', metavar='N', type = "integer", nargs='+',
                     help='an integer for the accumulator')
  parser$add_argument('--sum', dest='accumulate', action='store_const',
                     const='sum', default='max',
                     help='sum the integers (default: find the max)')
  parser$print_help()
  # default args for ArgumentParser()$parse_args are commandArgs(TRUE)
  # which is what you'd want for an Rscript but not for interactive use
  args <- parser$parse_args(c("--sum", "1", "2", "3"))
  accumulate_fn <- get(args$accumulate)
  print(accumulate_fn(args$integers))
}
#> usage: PROGRAM [-h] [--sum] N [N ...]
#> 
#> Process some integers
#> 
#> positional arguments:
#>   N           an integer for the accumulator
#> 
#> options:
#>   -h, --help  show this help message and exit
#>   --sum       sum the integers (default: find the max)
#> [1] 6