GitHub - trevorld/r-argparse: command-line optional and positional argument parser (original) (raw)

argparse: Command line optional and positional argument parser

argparse is an R package which provides a command line parser to be used with Rscript to write "#!" shebang scripts that gracefully accept positional and optional arguments and automatically generate usage.

To install the latest version released on CRAN use the following command:

install.packages("argparse")

To install the development version use the following command:

remotes::install_github("trevorld/r-argparse")

dependencies

The package has a Python dependency. It is easily satisfied if you have Python (version 3.2 or higher) on your PATH. Read the INSTALL file for more information if this doesn't describe you.

Additionally this package depends on the R packages R6, findpython, and jsonlite.

To run the unit tests you will need the suggested R package testthat and in order to build the vignette you will need the suggested R package knitrwhich in turn probably requires the system tool pandoc:

sudo apt install pandoc

examples

library("argparse") 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() usage: PROGRAM [-h] [--sum] N [N ...]

Process some integers

positional arguments: N an integer for the accumulator

optional arguments: -h, --help show this help message and exit --sum sum the integers (default: find the max)

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)) [1] 6

Beginning with version 2.0 argparse also supports argument groups:

parser = ArgumentParser(prog='PROG', add_help=FALSE) group1 = parser$add_argument_group('group1', 'group1 description') group1$add_argument('foo', help='foo help') group2 = parser$add_argument_group('group2', 'group2 description') group2$add_argument('--bar', help='bar help') parser$print_help() usage: PROG [-h] [--bar BAR] foo

optional arguments: -h, --help show this help message and exit

group1: group1 description

foo foo help

group2: group2 description

--bar BAR bar help

as well as mutually exclusive groups:

parser = ArgumentParser(prog='PROG') group = parser$add_mutually_exclusive_group() group$add_argument('--foo', action='store_true') group$add_argument('--bar', action='store_false') parser$parse_args('--foo') $bar [1] TRUE

$foo [1] TRUE

parser$parse_args('--bar') $bar [1] FALSE

$foo [1] FALSE

parser$parse_args(c('--foo', '--bar')) Error in "argparse::parse_args_output(output)" : parse error: usage: PROG [-h] [--foo | --bar] PROG: error: argument --bar: not allowed with argument --foo

and even basic support for sub-commands!:

create the top-level parser

parser = ArgumentParser(prog='PROG') parser$add_argument('--foo', action='store_true', help='foo help') subparsers = parser$add_subparsers(help='sub-command help')

create the parser for the "a" command

parser_a = subparsers$add_parser('a', help='a help') parser_a$add_argument('bar', type='integer', help='bar help')

create the parser for the "b" command

parser_b = subparsers$add_parser('b', help='b help') parser_b$add_argument('--baz', choices='XYZ', help='baz help')

parse some argument lists

parser$parse_args(c('a', '12')) $bar [1] 12

$foo [1] FALSE

parser$parse_args(c('--foo', 'b', '--baz', 'Z')) $baz [1] "Z"

$foo [1] TRUE

parser$print_help() usage: PROG [-h] [--foo] {a,b} ...

positional arguments: {a,b} sub-command help a a help b b help

optional arguments: -h, --help show this help message and exit --foo foo help

parser_a$print_help() usage: PROG a [-h] bar

positional arguments: bar bar help

optional arguments: -h, --help show this help message and exit

parser_b$print_help() usage: PROG b [-h] [--baz {X,Y,Z}]

optional arguments: -h, --help show this help message and exit --baz {X,Y,Z} baz help