Kernel density estimates with pattern overlays

A drop-in replacement for ggplot2::geom_density() that adds a pattern aesthetic. The pattern is clipped to the filled area under the density curve using the same device-independent in-R geometry as geom_ribbon_pattern().

Usage

geom_density_pattern(
  mapping = NULL,
  data = NULL,
  stat = "density",
  position = "identity",
  ...,
  na.rm = FALSE,
  orientation = NA,
  show.legend = NA,
  inherit.aes = TRUE
)

Arguments

mapping

Aesthetic mappings created by ggplot2::aes().

data

Data frame.

stat

Statistical transformation. Default "density".

position

Position adjustment. Default "identity".

...

Additional arguments passed to ggplot2::stat_density() (e.g. bw, adjust, kernel, n).

na.rm

If FALSE (default), missing values are removed with a warning.

orientation

Orientation of the layer. Default NA (automatic).

show.legend

Logical. Should this layer be included in the legend?

inherit.aes

If FALSE, overrides the default aesthetics.

Value

A ggplot2 layer.

Pattern aesthetics

In addition to all aesthetics accepted by ggplot2::geom_density(), this geom accepts:

pattern

Character name of the pattern. One of "none", "hatch", "crosshatch", "horizontal", "vertical", "dots", "weave", or a custom pattern registered with register_pattern(). Each base pattern (except "none") also has _dense and _sparse variants (e.g. "hatch_dense", "dots_sparse") for pre-set tighter or looser spacing.

pattern_colour

Colour of pattern lines/dots. Default "black".

pattern_linewidth

Line width for line-based patterns. Default 1.

pattern_spacing

Spacing between pattern elements in millimetres. Default 5. Smaller values produce denser patterns; larger values produce sparser patterns.

pattern_angle

Angle in degrees for hatch patterns. Default 45.

pattern_size

Dot radius in millimetres for the "dots" pattern. Default 0.5.

Limitations

orientation = "y" (horizontal densities) is not supported for the pattern overlay. The base density area renders correctly, but the pattern is silently skipped. Use coord_flip() on a vertical density as a workaround.

position = "stack" is supported: stacked densities are filled from 0 to the cumulative density, and the pattern follows the same filled region.

Examples

library(ggplot2)

# Single density with hatch pattern
ggplot(faithful, aes(waiting)) +
  geom_density_pattern(pattern = "hatch", fill = "lightblue") +
  theme_minimal()


# Multiple groups with different patterns
ggplot(mpg, aes(hwy, fill = drv, pattern = drv)) +
  geom_density_pattern(alpha = 0.6) +
  scale_pattern_manual(values = c("4" = "hatch", "f" = "crosshatch",
                                  "r" = "dots")) +
  scale_fill_brewer(palette = "Pastel1") +
  theme_minimal()