Command Line Flags in R Programming Language
Here’s the translation of the Go code to R, along with explanations in Markdown format suitable for Hugo:
R provides several packages for parsing command-line arguments. For this example, we’ll use the optparse
package, which offers functionality similar to the flag
package in the original example.
First, let’s install and load the optparse
package:
install.packages("optparse")
library(optparse)
Now, let’s create our command-line program:
library(optparse)
# Define the command-line options
option_list <- list(
make_option(c("-w", "--word"), type="character", default="foo",
help="a string [default=%default]"),
make_option(c("-n", "--numb"), type="integer", default=42,
help="an integer [default=%default]"),
make_option(c("-f", "--fork"), action="store_true", default=FALSE,
help="a boolean flag [default=%default]"),
make_option(c("-s", "--svar"), type="character", default="bar",
help="a string variable [default=%default]")
)
# Parse the command-line arguments
opt_parser <- OptionParser(option_list=option_list)
opts <- parse_args(opt_parser)
# Print out the parsed options and any remaining arguments
cat("word:", opts$word, "\n")
cat("numb:", opts$numb, "\n")
cat("fork:", opts$fork, "\n")
cat("svar:", opts$svar, "\n")
cat("args:", paste(opts$args, collapse=" "), "\n")
To run this program, save it as command_line_flags.R
and use the following command:
Rscript command_line_flags.R [options]
Here are some examples of how to use the program:
- Run with default values:
$ Rscript command_line_flags.R
word: foo
numb: 42
fork: FALSE
svar: bar
args:
- Provide values for all options:
$ Rscript command_line_flags.R -w opt -n 7 -f -s flag
word: opt
numb: 7
fork: TRUE
svar: flag
args:
- Provide some options and positional arguments:
$ Rscript command_line_flags.R -w opt a1 a2 a3
word: opt
numb: 42
fork: FALSE
svar: bar
args: a1 a2 a3
- Get help text:
$ Rscript command_line_flags.R -h
Usage: command_line_flags.R [options]
Options:
-w CHARACTER, --word=CHARACTER
a string [default=foo]
-n INTEGER, --numb=INTEGER
an integer [default=42]
-f, --fork
a boolean flag [default=FALSE]
-s CHARACTER, --svar=CHARACTER
a string variable [default=bar]
-h, --help
Show this help message and exit
Note that R’s optparse
package handles flags differently from the original example. In R, you can mix options and positional arguments, and all non-option arguments are collected in the args
field of the parsed options.
This example demonstrates how to use command-line flags in R, providing similar functionality to the original example while adhering to R’s conventions and the optparse
package’s structure.