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Pattern (hatch) fills

Source: R/pattern.R
patterns.Rd

Build a tiling pattern to use as a constant fill value on a filled mark, the texture counterpart of linear_gradient(). Distinguishing regions by texture (not only hue) keeps a plot legible in greyscale print and under colour-vision deficiency. Each constructor assembles a small tile and returns a vellum_pattern (via vellum::vl_pattern()); pass it straight to fill:

Usage

pattern_stripe(
  color = "grey20",
  bg = NA,
  angle = 45,
  spacing = 4,
  linewidth = 1,
  units = "mm"
)

pattern_crosshatch(
  color = "grey20",
  bg = NA,
  angle = 45,
  spacing = 4,
  linewidth = 1,
  units = "mm"
)

pattern_grid(
  color = "grey20",
  bg = NA,
  spacing = 4,
  linewidth = 1,
  units = "mm"
)

pattern_dot(color = "grey20", bg = NA, spacing = 4, size = 1.5, units = "mm")

pattern_checker(color = "grey20", bg = NA, size = 4, units = "mm")

Arguments

color

Line/dot colour (any R colour). Default "grey20".

bg

Background fill painted behind the motif, or NA (default) for a transparent tile so whatever is under the shape shows through.

angle

Stripe orientation in degrees, restricted to 0, 45, 90, or 135 (the orientations that tile seamlessly). Other values error.

spacing

Distance between repeats, in units. Default 4.

linewidth

Stripe / grid line width (as elsewhere in the package). Default 1.

units

Length unit for spacing/size: "mm" (default), "in", "pt", "npc", or "native".

size

For pattern_dot(), the dot diameter in units; for pattern_checker(), the square size in units.

Value

A vellum_pattern object, usable as a fill value.

Details

vplot(df) |> mark_bar(x = g, y = n, fill = pattern_stripe(angle = 45))

A pattern is an unscaled value, not a data-mapped channel (like a gradient). It applies to any filled mark: bars, areas, ribbons, rects, tiles, boxplots, violins, ridgelines, half-eyes, hulls/ellipses, and sf polygons. To vary the texture by a variable, map the pattern aesthetic instead (a discrete scale).

Patterns render on every backend (PNG, SVG, and — since the tile embeds as an image — PDF). The tile is rasterised at the scene resolution, so at extreme magnification it can soften; at ordinary sizes it is crisp.

See also

linear_gradient(), vellum::vl_pattern()

Examples

df <- data.frame(g = c("a", "b", "c"), n = c(3, 5, 2))
vplot(df) |> mark_bar(x = g, y = n, fill = pattern_crosshatch())