3D drop lines — geom_dropline

geom_dropline_3d() draws a line from each point to its projection on one or more faces of the panel, such as the floor, to help show where points lie in 3D. Use it alongside geom_point_3d(), and with position_on_face() to also mark where the points fall on the faces.

Usage

geom_dropline_3d(
  mapping = NULL,
  data = NULL,
  stat = StatIdentity3D,
  position = "identity",
  ...,
  faces = "zmin",
  scale_depth = TRUE,
  on_top = FALSE,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE
)

Arguments

mapping: Set of aesthetic mappings created by aes().
data: The data to be displayed in this layer.
stat: The statistical transformation to use on the data. Defaults to stat_identity_3d().
position: Position adjustment, defaults to "identity".
...: Other arguments passed on to layer(), such as aesthetics like colour, linewidth, linetype, and alpha.
faces: Faces to draw lines to: one or more of "xmin", "xmax", "ymin", "ymax", "zmin" (the default), and "zmax".
scale_depth: Controls depth-based scaling, drawing closer elements larger or thicker and farther ones smaller or thinner. TRUE (the default) applies full scaling and FALSE disables it; a number sets the strength directly, where 1 matches TRUE, 0 matches FALSE, values below 1 subdue the effect and values above 1 exaggerate it. This affects the layer only; use coord_3d(scale_depth = ) for panel and axis components.
on_top: If TRUE, the layer is drawn on top of the rest of the scene instead of being depth-sorted with it, so other geometry never hides or cuts it, e.g. to keep labels legible. The layers drawn on top are depth-sorted among themselves. Default FALSE.
na.rm: If FALSE, missing values are removed with a warning.
show.legend: Logical indicating whether this layer should be included in legends.
inherit.aes: If FALSE, overrides the default aesthetics.

Value

A ggplot2 layer.

Details

Faces are the faces of the panel's cube, so a drop line to "zmin" ends on the floor of the panel wherever the axis limits put it. Drop lines are depth-sorted with the rest of the scene, and split where they pass through polygons.

Aesthetics

geom_dropline_3d() understands the following aesthetics (required in bold): x, y, z, colour, linewidth (default 0.25), linetype, and alpha (default 0.5).

Examples

p <- ggplot(mtcars, aes(mpg, wt, qsec)) + coord_3d()

# Drop lines to the floor
p + geom_dropline_3d() + geom_point_3d()


# Drop lines to two side faces, ending in flat markers on those faces
p + geom_dropline_3d(faces = c("xmax", "ymax")) +
  geom_point_3d(position = position_on_face(c("xmax", "ymax")),
                flat = TRUE, alpha = .5) +
  geom_point_3d()


# Styled, with colour mapped
p + geom_dropline_3d(aes(colour = factor(cyl)), linetype = "dotted", alpha = 1) +
  geom_point_3d(aes(colour = factor(cyl)))