elp

The ellipsis ... is used in for example the plot function frequently to provide flexible visualization.

When we implement the plot function as the S3 generic method or others, we want to set the default graphics parameters such as xlab and title to the ellipsis ... in some cases.
Then, to implement proces for setting the default or for rejecting or accepting the user's specific value instead of the default is takes time and effort.

This package makes the process easily.

Installation

devtools::install_github("hosscine/elp")

Usage

Now, suppose that we want customized plot function like below:

• xlim = c(0, 2 * pi)
• xlab = "phase" (as default)
• col = "red" (as default).

bad example

plot2pi_bad <- function(x, ...) {
  elp <- list(...)
  elp$x <- x
  elp$xlim <- c(0, 2 * pi)
  if (is.null(elp$xlab)) elp$phase <- "phase"
  if (is.null(elp$col)) elp$col <- "red"
  do.call(plot, elp)
}

In this example, we must write long codes for just setting the default parameters.
And when user specify xlim, this function ignore it without warning.

good example

plot2pi_good <- function(x, ...){
  elp <- elp::overwrite_elp(..., x = x, xlim = c(0, 2 * pi))
  elp <- elp::softwrite_elp(..., append = elp, xlab = "phase", col = "red")
  do.call(plot, elp)
}

This example is more simpler.
If user specify xlim, the function warns that conflict was occured. (controlable by warn argument)

Note

If you chain elp::overwrite_elp and elp::softwrite_elp, use overwrite_elp() firstly like good example code or set warn = FALSE.

Templete

  elp <- elp::overwrite_elp(..., x = x)
  elp <- elp::softwrite_elp(..., append = elp)
  do.call(plot, elp)