R/geom_highlight_government.R

In ggparliament: Parliament Plots

#' Highlight governments or parties in control of the legislature by encircling the points.
#' @param expr Expr refers to the observation that you wish to highlight.
#' @param colour Colour of the highlight
#' @param size Size of highlighter
#' @param shape Shape of highlight
#' @param stroke Size of stroke shape
#' @examples
#' data <- election_data[
#'   election_data$country == "USA" &
#'   election_data$house == "Representatives" &
#'   election_data$year == "2016",
#' ]
#' usa_data <- parliament_data(
#'   election_data = data,
#'   type = "semicircle",
#'   party_seats = data$seats,
#'   parl_rows = 8
#' )
#' ggplot2::ggplot(usa_data, ggplot2::aes(x, y, colour = party_long)) +
#'   geom_parliament_seats() +
#'   geom_highlight_government(government == 1) +
#'   theme_ggparliament()
#' @usage geom_highlight_government(expr, colour, size, shape, stroke)
#' @author Zoe Meers
#' @source https://yutani.rbind.io/post/2017-11-07-ggplot-add/
#' @export
#' @importFrom ggplot2 ggplot_add

geom_highlight_government <- function(expr, colour = "black", size = 3, shape = 19, stroke = 1.8) {
  structure(list(
    expr = rlang::enquo(expr),
    colour = colour,
    size = size,
    shape = shape,
    stroke = stroke
  ), class = "highlight")
}


#' @export
ggplot_add.highlight <- function(object, plot, object_name) {
  new_data <- dplyr::filter(plot$data, !!object$expr)
  new_layer <- ggplot2::geom_point(
    data = new_data,
    mapping = plot$mapping,
    colour = object$colour,
    show.legend = FALSE,
    size = object$size,
    stroke = object$stroke,
    shape = object$shape
  )
  plot$layers <- append(new_layer, plot$layers)
  plot
}