SF polygon maps with pattern overlays

A drop-in replacement for ggplot2::geom_sf() that adds a pattern aesthetic. Patterns are clipped to the exact polygon boundary using the same device-independent in-R geometry as geom_polygon_pattern(). Requires the sf package.

Usage

geom_sf_pattern(
  mapping = ggplot2::aes(),
  data = NULL,
  stat = "sf",
  position = "identity",
  ...,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE
)

Arguments

mapping

Aesthetic mappings created by ggplot2::aes().

data

An sf data frame or compatible object.

stat

Statistical transformation. Default "sf".

position

Position adjustment. Default "identity".

...

Other arguments passed to the layer.

na.rm

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

show.legend

Logical or character. Should this layer be included in the legends?

inherit.aes

If FALSE, overrides the default aesthetics.

Value

A ggplot2 layer.

Note

GEOMETRYCOLLECTION: rows with GEOMETRYCOLLECTION geometry produce a warning and no pattern overlay; the base geometry is still rendered.

Holes in polygons: inner rings (holes / donuts) are silently ignored — the pattern fills the entire outer boundary including hole areas. This is a limitation of the in-R polygon clipping approach.

Pattern aesthetics

In addition to all aesthetics accepted by ggplot2::geom_sf(), 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. Named density variants (e.g. "hatch_dense") bake in a pre-set spacing multiplier but still respect explicit pattern_spacing values.

pattern_angle

Angle in degrees for hatch patterns. Default 45.

pattern_size

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

Geometry type support

POLYGON and MULTIPOLYGON features receive pattern overlays. POINT and LINESTRING features render correctly via the base ggplot2::geom_sf() but without pattern overlays (silently skipped). Mixed geometry types in the same layer are supported.

Examples

if (requireNamespace("sf", quietly = TRUE)) {
  library(ggplot2)
  library(sf)

  sq1 <- st_polygon(list(cbind(c(0,1,1,0,0), c(0,0,1,1,0))))
  sq2 <- st_polygon(list(cbind(c(1,2,2,1,1), c(0,0,1,1,0))))
  df  <- data.frame(
    region  = c("A", "B"),
    pattern = c("hatch", "dots"),
    geometry = st_sfc(sq1, sq2, crs = 4326)
  )
  sf::st_geometry(df) <- "geometry"

  ggplot(df) +
    geom_sf_pattern(aes(fill = region, pattern = pattern)) +
    scale_pattern_identity(guide = "legend") +
    scale_fill_brewer(palette = "Pastel1") +
    theme_minimal()
}
#> Linking to GEOS 3.12.1, GDAL 3.8.4, PROJ 9.4.0; sf_use_s2() is TRUE