R/ggplot.R

In FastUtils: Fast, Readable Utility Functions

#' Get the dimensions of a ggplot Object
#'
#' This function retrieves the minimum and maximum x and y dimensions of a
#' ggplot object. Note that it is the dimension of the plot within the x and y
#' axis and not the dimensions of the actual output image itself. This may be
#' useful for numerical computations when modifying plots, but can be slow since
#' it builds the actual plot first.
#'
#' @param plt A ggplot object.
#'
#' @return A list with elements `xr` (a vector of xmin and xmax) and `yr` (a
#' vector of ymin and ymax).
#' @export
#' @keywords ggplot
#' @examples
#' library(ggplot2)
#' getPlotDims(ggplot(mtcars) + geom_point(aes(mpg, cyl)))
#'
getPlotDims <- function(plt) {
    assertthat::assert_that(ggplot2::is.ggplot(plt))
    builtPlotLayout <- ggplot2::ggplot_build(plt)$layout
    list(
        xr = builtPlotLayout$panel_scales_x[[1]]$range$range,
        yr = builtPlotLayout$panel_scales_y[[1]]$range$range
    )
}