Add Layers to an hd Object — +.hd • highdir

Implements the + operator for hd() objects, mirroring how ggplot2 builds plots incrementally. Recognised right-hand sides:

Usage

# S3 method for class 'hd'
e1 + e2

Arguments

e1: An hd object (left-hand side).
e2: An hd_geom or hd_opts object (right-hand side).

Value

The updated hd object (invisibly, so the chain prints once).

Details

hd_geom object: Sets the geometry (from any hd_geom_*() call). Adding a second geom replaces the first — highdir renders one geometry per figure.
hd_opts object: Sets presentation options. Adding a second hd_opts replaces the first.

Unknown right-hand sides produce an informative error rather than silently being ignored.

Examples

df <- data.frame(age = c("18-24", "25-34"), pct = c(42, 55))

# Chain layers
p <- hd(df, x = "age", y = "pct") +
  hd_geom_column() +
  hd_opts(title = "Demo")

# Reuse a partial object with different opts
base <- hd(df, x = "age", y = "pct") + hd_geom_column()
base + hd_opts(title = "English title")
base + hd_opts(title = "Norsk tittel")