geom_kodom_line: Swimlane line plot for longitudinal trajectories

In ggkodom: Visualize Individual Longitudinal Trajectories

Swimlane line plot for longitudinal trajectories

Description

Draws one horizontal colored path per subject. Time maps to x, subject identity maps to id (which the stat converts to integer lane positions on the y axis), and a measured value maps to colour. The colour transitions smoothly between consecutive observations via interpolated sub-segments.

Usage

geom_kodom_line(
  mapping = NULL,
  data = NULL,
  stat = StatKodomLine,
  position = "identity",
  ...,
  sort_by = "none",
  n_max = Inf,
  show_points = TRUE,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE
)

Arguments

mapping	Set of aesthetic mappings created by ggplot2::aes().
data	A data frame. If NULL, inherits from the plot.
stat	The stat to use. Defaults to StatKodomLine.
position	Position adjustment, almost always "identity".
...	Other arguments passed to ggplot2::layer().
sort_by	Lane ordering. One of "none" (default), "mean", "mean_asc", "first", "last" — all refer to the colour variable.
n_max	Maximum number of subjects to display. A random sample is taken when exceeded. Default Inf (all subjects).
show_points	If TRUE (default), draws a point at every observation. Set to FALSE, or map shape = NA / size = 0, to suppress points.
na.rm	If TRUE, silently remove rows with missing required aesthetics.
show.legend	Logical. Should this layer appear in the legend?
inherit.aes	If FALSE, overrides the default aesthetics.

Details

Lane ordering is controlled by sort_by. With many subjects, consider suppressing y-axis labels via theme(axis.text.y = element_blank()).

Value

A ggplot2 layer object.

Aesthetics

Required aesthetics are shown in bold. size and linewidth are intentionally independent: each controls a different graphical element.

• x — time variable (numeric or Date)

• id — subject identifier; determines lane position on the y axis

• colour — color of both the connecting path and the point border

• fill — point interior color for filled shapes (21–25); no effect on path

• size — point size only; set to NA or 0 to suppress points

• linewidth — path width only; does not affect observation points

• alpha — transparency applied to both path and points

• shape — point shape (default 19). Set to NA to suppress points.

• stroke, linetype — point border width / path line type

Examples

library(ggplot2)
df <- data.frame(
  subject_id = rep(1:5, each = 4),
  time = rep(1:4, 5),
  visit_month = rep(1:4, 5),
  value = rep(1:4, 5),
  hba1c = rep(1:4, 5),
  arm = rep(c("Treatment", "Control"), c(12, 8))
)
ggplot(df, aes(x = time, id = subject_id, colour = hba1c)) +
  geom_kodom_line(sort_by = "mean", n_max = 50) +
  scale_colour_kodom() +
  theme_kodom()

ggkodom documentation built on June 20, 2026, 5:06 p.m.