Question

CommandArgs(trailingOnly = TRUE) in R:

a) Retrieves all command-line arguments
b) Retrieves only trailing command-line arguments
c) Sets command-line arguments
d) Clears command-line arguments

Answer 1

The function commandArgs(trailing Only = TRUE) in R retrieves only the trailing command-line arguments, which are arguments following a double hyphen or non-option arguments if no double hyphen is present.

Step-by-step explanation:

The function commandArgs(trailing Only = TRUE) in R has a specific role in the context of command-line interaction with the R script. When you use this function with the argument trailing Only set to TRUE, it retrieves only trailing command-line arguments. The 'trailing' arguments refer to those that appear after a double hyphen (--) in the command line. If no double hyphen is used, commandArgs(trailingOnly = TRUE) will return all the arguments that do not include options (which are usually prefixed with a hyphen, such as -f or --file).

To clarify with an example, if an R script is invoked from the command line like this: Rscript my_script.R --arg1 val1 -- --trailing1 trailing2, calling commandArgs(trailing Only = TRUE) within my_script.R will only return c("--trailing1", "trailing2").