R/geom_flat_violin.R

In qdercon/pstpipeline: Probabilistic Selection Task (PST) pipeline: parsing, analysis, simulation, and plotting

#' @noRd
#' @keywords internal

# Adapted from https://github.com/RainCloudPlots/RainCloudPlots (R_rainclouds.R)
# Citation: https://wellcomeopenresearch.org/articles/4-63
# Defining the geom_flat_violin function ---------------------------------------

"%||%" <- function(a, b) {
  if (!is.null(a)) a else b
}

geom_flat_violin <-
  function(mapping = NULL,
           data = NULL,
           stat = "ydensity",
           position = "dodge",
           trim = TRUE,
           scale = "area",
           show.legend = NA,
           inherit.aes = TRUE,
           ...) {

    ggplot2::layer(
      data = data,
      mapping = mapping,
      stat = stat,
      geom = GeomFlatViolin,
      position = position,
      show.legend = show.legend,
      inherit.aes = inherit.aes,
      params = list(
        trim = trim,
        scale = scale,
        ...
      )
    )
  }

GeomFlatViolin <-
  ggplot2::ggproto("GeomFlatViolin", ggplot2::Geom,
    setup_data = function(data, params) {
      data$width <- data$width %||%
        params$width %||% (ggplot2::resolution(data$x, FALSE) * 0.9)

      # ymin, ymax, xmin, and xmax define the bounding rectangle for each group
      data |>
        dplyr::group_by(group) |>
        dplyr::mutate(
          ymin = min(y),
          ymax = max(y),
          xmin = x,
          xmax = x + width / 2
        )
    },

    draw_group = function(data, panel_scales, coord) {
      # Find the points for the line to go all the way around
      data <- transform(data,
        xminv = x,
        xmaxv = x + violinwidth * (xmax - x)
      )

      # Make sure it's sorted properly to draw the outline
      newdata <- rbind(
        dplyr::arrange(transform(data, x = xminv), y),
        dplyr::arrange(transform(data, x = xmaxv), -y)
      )

      # Close the polygon: set first and last point the same
      # Needed for coord_polar and such
      newdata <- rbind(newdata, newdata[1, ])

      ggplot2:::ggname(
        "geom_flat_violin",
        ggplot2::GeomPolygon$draw_panel(newdata, panel_scales, coord)
      )
    },

    draw_key = ggplot2::draw_key_polygon,

    default_aes = ggplot2::aes(
      weight = 1, colour = "grey20", fill = "white", size = 0.5,
      alpha = NA, linetype = "solid"
    ),

    required_aes = c("x", "y")
  )