CODEWITHSUNDEEP
rfunction
Rorschach
Rorschach

Reputation: 32416

Pass argument as default argument to all unnamed function arguments

What is a nice way to pass a default argument to all the unspecified arguments of a function? For example, using list.dirs there are three arguments: path, full.names, and recursive. In this example. I would like to supply the path argument and then a default argument (FALSE) that gets passed to all the remaining function arguments. In this example it is obviously no problem to simply specify FALSE to the two remaining arguments, but what if there were a lot of arguments that I wanted to specify with the default?

Something equivalent to 

list.dirs(path=".", full.names = FALSE, recursive = FALSE)

but with something like (which doesn't work)

do.call("list.dirs", list(path=".", FALSE))

or (also doesn't work)

do.call("list.dirs", list(path=".", rep(FALSE, 2)))

Upvotes: 1

Views: 90

Answers (1)

user5219763
user5219763

Reputation: 1294

Use formals() to return a list of arguments, length() to get the number of arguments, and replicate to create a list of 'default' arguments the right length (minus the arguments set manually).

do.call("list.dirs", c(list("."), replicate(length(formals("list.dirs"))-1,expr = "FALSE")))

Upvotes: 2

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