Error: bad 'S3method' directive: S3method(plot) in R

Question

I am writing a R package using devtools. Now I have a generic function plot that can take different classes (e.g. plot.fact, plot.numer, etc.). In the .R file of plot.fact, I use #' comment for documentations in a roxygen way. Besides other items, I specify the following comments:

#' @rdname plot
#' @method plot fact
#' @S3method plot fact
#' @export

However, when I run check('pkg') the following error message appear: Error: bad 'S3method' directive: S3method(plot). Is there anything wrong with how I write the comments? Or do I have to write a plot <- function(x,...) UseMethod("plot") before the function plot.fact? Thanks!

UPDATE

To be more precise, my plot.fact function does not have a single argument x; instead, it has many extra parameters to customize the plot. The arguments are

plot.fact <- function(x, conf.env=0.95, data.note="", leg.cex=1, ...)

According to Hadley's suggestion, I use

#' @rdname plot
#' @method plot fact
#' @export

But the error is still bad 'S3method' directive... Do I need to write down

plot <- function(x, conf.env=0.95, data.note="", leg.cex=1, ...) {
  UseMethod("plot")
}

before the definition of plot.fact? Thanks!

Answer 1

• If you want to document the method use @method plot fact + @export.
• If you don't want to document it, use @s3method plot fact.

You shouldn't ever have @method and @s3method in the same block.