Skip to contents

Label the lines drawn by geom_slice()

Source: R/geom_slice_text.R
geom_slice_text.Rd

geom_slice_text() writes a text label at the end of each line drawn by the plot's geom_slice() layers. Multi-value predict_vars draw visually identical lines with nothing distinguishing them; labels fix that, and double as a legend replacement for grouping aesthetics.

Usage

geom_slice_text(
  style = "variable",
  location = "right",
  offset = 5,
  hjust = NULL,
  vjust = NULL,
  color = NULL,
  expand = TRUE
)

Arguments

style

How to write the labels: "variable" (default) writes "x2: 0"; "value" writes the bare "0"; "legend" writes bare values plus a key in the panel's top-right corner naming the variables ("labels: x2; x3").

location

Which end of the line to label: "right" (default) or "left".

offset

Gap between the line end and the label edge, in points (default 5). The gap is constant regardless of label text, axis range, or plot size.

hjust, vjust

Manual text justification. Default NULL anchors the label at the line end, displaced by offset; setting hjust yourself disables the automatic offset entirely.

color

Label color. Default NULL inherits each line's color.

expand

If TRUE (default), widen the x-range on the label side so the labels fit (plus y-headroom for the "legend" key). FALSE leaves the scales alone. Only the expansion is touched: a scale_x_*() you set yourself keeps its limits, breaks, name and transform, and an expansion you set on the side away from the labels is kept as well. The room reserved is the widest label's drawn width measured against the panel's own width, taken from the graphics device open when the layer is added; a plot re-sized much narrower afterwards may still clip. Labels needing more than half the panel are clipped with a warning rather than crowding out the data.

Value

An object that adds the label layers when added to a ggplot.

Details

It takes no model or predict_vars — everything is borrowed from the plot's existing geom_slice() layers, so add it after them. Labels describe the predict_vars values ("x2: 0", joined with "; " when several variables are crossed); when the slice layer has no predict_vars, labels describe the grouping aesthetic instead ("g: A"). Each label inherits its line's color.

See also

geom_slice() for the layers being labeled; geom_slice_subtitle() / geom_slice_caption() to describe the slice in the plot's text instead.

Examples

library(ggplot2)

# One label per predict_vars value
model <- lm(Sepal.Length ~ Sepal.Width + Petal.Length, data = iris)
ggplot(iris, aes(Petal.Length, Sepal.Length)) +
  geom_point() +
  geom_slice(model, predict_vars = list(Sepal.Width = c(2, 3, 4))) +
  geom_slice_text()


# A projection band, labeled on each edge
ggplot(iris, aes(Petal.Length, Sepal.Length)) +
  geom_point() +
  geom_slice(model, band = TRUE) +
  geom_slice_text()
#> Band range for `Sepal.Width` not specified - used the min/max data range: 2 to 4.4.
#>     To choose the range, use 'predict_vars = list(Sepal.Width = c(2, 4.4))'.


# Labels take the color of their group
model2 <- lm(hwy ~ displ * drv + cyl, data = mpg)
ggplot(mpg, aes(displ, hwy, color = drv)) +
  geom_point() +
  geom_slice(model2, predict_vars = list(cyl = c(4, 8))) +
  geom_slice_text()


# Lines defined by several variables read best with a corner key
ggplot(mpg, aes(displ, hwy)) +
  geom_point() +
  geom_slice(model2, predict_vars = list(cyl = c(4, 8), drv = c("f", "r"))) +
  geom_slice_text(style = "legend")