annotation_scale function

data

Spatial-aware scalebar annotation

Format

An object of class GeomScaleBar (inherits from Geom, ggproto, gg) of length 5.

annotation_scale(
  mapping = NULL,
  data = NULL,
  ...,
  plot_unit = NULL,
  bar_cols = c("black", "white"),
  line_width = 1,
  height = unit(0.25, "cm"),
  pad_x = unit(0.25, "cm"),
  pad_y = unit(0.25, "cm"),
  text_pad = unit(0.15, "cm"),
  text_cex = 0.7,
  text_face = NULL,
  text_family = "",
  tick_height = 0.6
)

GeomScaleBar

Arguments

• mapping, data, ...: See Aesthetics
• plot_unit: For non-coord_sf applications, specify the unit for x and y coordinates. Must be one of km, m, cm, mi, ft, or in.
• bar_cols: Colours to use for the bars
• line_width: Line width for scale bar
• height: Height of scale bar
• pad_x, pad_y: Distance between scale bar and edge of panel
• text_pad, text_cex, text_face, text_family: Parameters for label
• tick_height: Height of ticks relative to height of scale bar

Returns

A ggplot2 layer.

Aesthetics

The following can be used as parameters or aesthetics. Using them as aesthetics is useful when facets are used to display multiple panels, and a different (or missing) scale bar is required in different panels. Otherwise, just pass them as arguments to annotation_scale.

• width_hint: The (suggested) proportion of the plot area which the scalebar should occupy.
• unit_category: Use "metric" or "imperial" units.
• style: One of "bar" or "ticks"
• location: Where to put the scale bar ("tl" for top left, etc.)
• line_col and text_col: Line and text colour, respectively

Examples

cities <- data.frame(
  x = c(-63.58595, 116.41214),
  y = c(44.64862, 40.19063),
  city = c("Halifax", "Beijing")
)

ggplot(cities) +
  geom_spatial_point(aes(x, y), crs = 4326) +
  annotation_scale() +
  coord_sf(crs = 3995)