gf_resid_fun: Add Residual Lines from a Function to a Plot

In coursekata: Packages and Functions for 'CourseKata' Courses

Add Residual Lines from a Function to a Plot

Description

Usage

gf_resid_fun(
  object = NULL,
  gformula = NULL,
  data = NULL,
  ...,
  fun,
  linewidth = 0.2,
  xlab,
  ylab,
  title,
  subtitle,
  caption,
  geom = coursekata::GeomResid,
  stat = coursekata::StatResid,
  position = "identity",
  show.legend = NA,
  show.help = NULL,
  inherit = TRUE,
  environment = parent.frame()
)

Arguments

object	A ggformula plot object, typically created with gf_point().
gformula	Not used. gf_resid_fun() measures a function, not an aesthetic formula; a function given positionally lands here and is moved to fun.
data	Not used. The residuals are measured over the data the plot was built from. Anything supplied here is left for ggformula and ggplot2 to answer, exactly as it is for any other gf_ layer.
...	Additional arguments. Typically these are (a) ggplot2 aesthetics to be set with attribute = value, such as color, alpha or linetype, (b) ggplot2 aesthetics to be mapped with attribute = ~ expression, or (c) attributes of the layer as a whole.
fun	A function of one argument. It is called on the x values the plot draws and must return one predicted y for each of them. May be given positionally or as ⁠fun =⁠.
linewidth	The width of the residual lines. Default is 0.2. Must be named.
xlab, ylab, title, subtitle, caption	Labels for the plot.
geom, stat, position	Not set by the caller. A residual is drawn by its own geom and stat, and moved by the position the observations are already drawn with, so that a segment stays on the point it belongs to.
show.legend	Whether this layer contributes to the legend.
show.help	Print the layer's own help instead of drawing.
inherit	Whether the layer inherits the plot's aesthetics. The axes and the prediction are stated outright; everything else – a mapped color, for instance – is inherited from the plot.
environment	The environment mappings are resolved in.

Details

Draws residual lines from predicted values to the observed points, using a user-supplied function of x (e.g., the function plotted with gf_function()). Where gf_resid() measures a fitted model, this measures a function you wrote: it is called on the x values the plot draws, and each residual runs from the prediction to the observation.

Value

A ggplot object with residual lines added.

Examples

set.seed(1)
df <- data.frame(X = 1:10, Y = 2 + 3 * (1:10) + rnorm(10))
my_fun <- function(x) 2 + 3 * x

gf_point(Y ~ X, data = df) %>%
  gf_function(my_fun) %>%
  gf_resid_fun(my_fun, color = "red", alpha = 0.5)

coursekata documentation built on Sept. 22, 2026, 1:08 a.m.