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(plot, fun, linewidth = 0.2, ...)

Arguments

plot	A ggformula/ggplot object, typically created with gf_point().
fun	A function that takes a numeric vector x and returns predicted y.
linewidth	Numeric width of the residual lines. Default 0.2.
...	Additional aesthetics passed to ggplot2::geom_segment(), e.g., color, alpha, linetype.

Details

Draws vertical residual lines from observed points to predicted values computed by a user-supplied function of x (e.g., the function plotted with gf_function()).

Value

A ggplot object with residual segments 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 March 11, 2026, 1:06 a.m.