man-roxygen/param_on.R

In great-northern-diver/loon.tourr: Tour in 'Loon'

#' @param on if the \code{x} or \code{by} is a formula,
#' an optional data frame containing the variables in the \code{x} or \code{by}.
#' If the variables are not found in data, they are taken from environment,
#' typically the environment from which the function is called.