Add in geoms for labelled first and final points

These are adaptations of geom_finallabel used by Liz in previous reports.

Initial version:

### geom_firstlabel()

#' Line with a dot on the first observation
#' @description geom_firstlabel() draws a ggplot2::geom_text()
#' at the observation with the maximum x value for each group.
#' @inheritParams ggplot2::geom_text
#' @param nudge_x_perc Amount to nudge label along the x-axis, expressed as a
#' percentage of the data range along the x-axis. The default is 1.5, which
#' will nudge the text 1.5% of the data range from the first point. This is applied
#' in addition to nudge_x, which nudges the text a specific number of data units.
#' @section Aesthetics:
#'   \code{geom_text()} understands the following aesthetics (required aesthetics are in bold):
#'   \itemize{
#'     \item \strong{\code{x}}
#'     \item \strong{\code{y}}
#'     \item \strong{\code{label}}
#'     \item \code{alpha}
#'     \item \code{angle}
#'     \item \code{colour}
#'     \item \code{family}
#'     \item \code{fontface}
#'     \item \code{group}
#'     \item \code{hjust}
#'     \item \code{lineheight}
#'     \item \code{size}
#'     \item \code{vjust}
#'   }
#'
#' Learn more about setting these aesthetics in \code{vignette("ggplot2-specs")}.
#' @seealso ggplot2::geom_text
#' @export
#' @rdname geom_firstlabel
#' @examples
#' library(ggplot2)
#'
#'ggplot(ggplot2::economics_long, aes(x = date, y = value)) +
#'   geom_linepoint(aes(col = variable)) +
#'   geom_firstlabel(aes(label = value)) +
#'   facet_wrap(~variable)
geom_firstlabel <-
  function(mapping = NULL,
           data = NULL,
           stat = "identity",
           position = "identity",
           nudge_x = 0,
           nudge_y = 0,
           nudge_x_perc = 1.5,
           na.rm = FALSE,
           show.legend = FALSE,
           inherit.aes = TRUE,
           ...) {
    if (!missing(nudge_x) || !missing(nudge_y)) {
      if (!missing(position)) {
        stop("You must specify either position or nudge_x/nudge_y.")
      }

      position <- position_nudge(nudge_x, nudge_y)
    }

    ggplot2::layer(
      data = data,
      mapping = mapping,
      stat = stat,
      geom = GeomfirstLabel,
      position = position,
      show.legend = show.legend,
      inherit.aes = inherit.aes,
      params = list(
        na.rm = na.rm,
        nudge_x_perc = nudge_x_perc,
        ...
      )
    )
  }

#' @export
#' @rdname geom_firstlabel
GeomfirstLabel <- ggplot2::ggproto(
  "GeomfirstLabel",
  ggplot2::Geom,
  extra_params = c("na.rm", "nudge_x_perc"),
  setup_data = function(data, params) {
    ggplot2::GeomText$setup_data(data, params)
  },
  draw_group = function(data,
                        panel_params,
                        coord,
                        nudge_x_perc,
                        flipped_aes = FALSE) {
    x_range <- range(data$x)
    x_min <- x_range[1]
    x_max <- x_range[2]
    data <- data[data$x == x_min, ]
    data$x <- data$x - ((x_max - x_min) * (nudge_x_perc / 100))


    ggplot2::GeomText$draw_panel(
      data,
      panel_params,
      coord
    )
  },
  draw_key = ggplot2::draw_key_text,
  required_aes = c("x", "y", "label"),
  default_aes = ggplot2::aes(
    colour = ggplot2::GeomText$default_aes$colour,
    size = ggplot2::GeomText$default_aes$size,
    angle = ggplot2::GeomText$default_aes$angle,
    hjust = 1,
    vjust = ggplot2::GeomText$default_aes$vjust,
    alpha = ggplot2::GeomText$default_aes$alpha,
    family = ggplot2::GeomText$default_aes$family,
    fontface = ggplot2::GeomText$default_aes$fontface,
    lineheight = 0.9
  )
)


#' Line with a dot on the final observation
#' @description geom_linepoint() draws a ggplot2::geom_line() and adds a
#' ggplot2::geom_point() at the observation with the maximum x value for each
#' group.
#' @inheritParams ggplot2::geom_line
#' @section Aesthetics:
#' \code{geom_linepoint()} understands the following aesthetics (required aesthetics are in bold):
#'   \itemize{
#'     \item \strong{\code{x}}
#'     \item \strong{\code{y}}
#'     \item \code{alpha}
#'     \item \code{colour}
#'     \item \code{group}
#'     \item \code{linetype}
#'     \item \code{pointfill}
#'     \item \code{pointshape}
#'     \item \code{pointsize}
#'     \item \code{pointstroke}
#'     \item \code{pointshape}
#'     \item \code{linewidth}
#'     \item \code{weight}
#'   }
#' The aesthetics that begin with 'point' (eg. pointfill) are passed to
#' geom_point() - for example pointfill is passed to the fill aesthetic
#' of geom_point().
#'
#' The x, y, alpha, colour, and group aesthetics are passed to both
#' geom_line() and geom_point().
#'
#' The linetype, linewidth, and weight aesthetics are passed to geom_line().
#'
#' Learn more about setting these aesthetics in \code{vignette("ggplot2-specs")}.
#' @seealso ggplot2::geom_line, ggplot2::geom_point
#' @rdname geom_linepoint
#' @export
#' @examples
#' library(ggplot2)
#'
#'ggplot(ggplot2::economics_long, aes(x = date, y = value)) +
#'   geom_linepoint(aes(col = variable)) +
#'   facet_wrap(~variable)
geom_linepoint <-
  function(mapping = NULL,
           data = NULL,
           stat = "identity",
           position = "identity",
           na.rm = FALSE,
           show.legend = NA,
           inherit.aes = TRUE,
           ...) {
    ggplot2::layer(
      data = data,
      mapping = mapping,
      stat = stat,
      geom = GeomLinePoint,
      position = position,
      show.legend = show.legend,
      inherit.aes = inherit.aes,
      params = list(
        na.rm = na.rm,
        ...
      )
    )
  }

#' @rdname geom_linepoint
#' @export
GeomLinePoint <- ggplot2::ggproto(
  "GeomLinePoint",
  ggplot2::Geom,
  extra_params = c("na.rm"),
  setup_data = function(data, params) {
    ggplot2::GeomLine$setup_data(data, params)
  },
  draw_group = function(data,
                        panel_params,
                        coord,
                        lineend = "butt",
                        linejoin = "round",
                        linemitre = 10,
                        size = 5,
                        flipped_aes = FALSE) {
    point <- data
    point <- point[point$x == point$x[length(point$x)], ]
    point$size <- point$pointsize
    point$fill <- point$pointfill
    point$shape <- point$pointshape
    point$stroke <- point$pointstroke
    point$shape <- point$pointshape

    if (utils::packageVersion("ggplot2") < "3.4.0") {
      names(data)[names(data) == "linewidth"] <- "size"
    }

    path <- transform(data, alpha = NA)

    grid::gList(
      ggplot2::GeomLine$draw_panel(
        path,
        panel_params,
        coord,
        lineend = lineend,
        linejoin = linejoin,
        linemitre = linemitre
      ),
      ggplot2::GeomPoint$draw_panel(point, panel_params, coord)
    )
  },
  draw_key = ggplot2::draw_key_smooth,
  required_aes = c("x", "y"),
  non_missing_aes = c(
    "linewidth", "shape", "colour", "pointsize",
    "pointstroke", "pointfill", "pointshape"
  ),
  default_aes = ggplot2::aes(
    pointsize = 2.5,
    pointfill = "white",
    pointshape = 21,
    shape = 19,
    colour = "black",
    linewidth = 1,
    alpha = 1,
    pointstroke = 1.5,
    linetype = 1,
    weight = 1
  )
)