Add position_nudgestack

Author: Thomas Knecht

R/position-nudgestack.R

@@ -0,0 +1,117 @@
+#' Simultaneously nudge and stack
+#'
+#' This is primarily used for set stacked columns between the ticks on the
+#' x-axis.
+#'
+#' @family position adjustments
+#' @param x,y Amount of vertical and horizontal distance to move.
+#' @param vjust Vertical adjustment for geoms that have a position
+#'   (like points or lines), not a dimension (like bars or areas). Set to
+#'   `0` to align with the bottom, `0.5` for the middle,
+#'   and `1` (the default) for the top.
+#' @param reverse If `TRUE`, will reverse the default stacking order.
+#'   This is useful if you're rotating both the plot and legend.
+#' @export
+#' @examples
+#' data <- mtcars
+#' ggplot() +
+#'   geom_col(
+#'     data,
+#'     aes(x = cyl, y = gear, fill = gear),
+#'     position = position_nudgestack(x = 1)
+#'   )
+position_nudgestack <- function(x = 0, y = 0, vjust = 1, reverse = FALSE) {
+  ggproto(NULL, PositionNudgeStack,
+    x = x,
+    y = y,
+    vjust = vjust,
+    reverse = reverse
+  )
+}
+
+
+
+#' @rdname ggplot2-ggproto
+#' @format NULL
+#' @usage NULL
+#' @export
+PositionNudgeStack <- ggproto("PositionNudgeStack", Position,
+  x = 0,
+  y = 0,
+  type = NULL,
+  vjust = 1,
+  fill = FALSE,
+  reverse = FALSE,
+
+  setup_params = function(self, data) {
+    list(
+      x = self$x,
+      y = self$y,
+      var = if (!is.null(self$var)) self$var else stack_var(data),
+      fill = self$fill,
+      vjust = self$vjust,
+      reverse = self$reverse
+    )
+  },
+
+  setup_data = function(self, data, params) {
+    if (is.null(params$var)) {
+      return(data)
+    }
+
+    data$ymax <- switch(params$var,
+      y = data$y,
+      ymax = ifelse(data$ymax == 0, data$ymin, data$ymax)
+    )
+
+    remove_missing(
+      data,
+      vars = c("x", "xmin", "xmax", "y"),
+      name = "position_stack"
+    )
+  },
+
+  compute_layer = function(self, data, params, layout) {
+    if (is.null(params$var)) {
+      return(data)
+    }
+
+    negative <- data$ymax < 0
+    negative[is.na(negative)] <- FALSE
+
+    neg <- data[negative, , drop = FALSE]
+    pos <- data[!negative, , drop = FALSE]
+
+    if (any(negative)) {
+      neg <- collide(neg, NULL, "position_stack", pos_stack,
+        vjust = params$vjust,
+        fill = params$fill,
+        reverse = params$reverse
+      )
+    }
+    if (any(!negative)) {
+      pos <- collide(pos, NULL, "position_stack", pos_stack,
+        vjust = params$vjust,
+        fill = params$fill,
+        reverse = params$reverse
+      )
+    }
+
+    data <- rbind(neg, pos)[match(seq_len(nrow(data)), c(which(negative), which(!negative))), ]
+
+
+
+    # transform only the dimensions for which non-zero nudging is requested
+    if (any(params$x != 0)) {
+      if (any(params$y != 0)) {
+        transform_position(data, function(x) x + params$x, function(y) y + params$y)
+      } else {
+        transform_position(data, function(x) x + params$x, NULL)
+      }
+    } else if (any(params$y != 0)) {
+      transform_position(data, NULL, function(y) y + params$y)
+    } else {
+      data # if both x and y are 0 we don't need to transform
+    }
+  }
+)