Scale for vector magnitudes

Allows to control the size of the arrows in geom_arrow. Highly experimental.

scale_mag(
  name = ggplot2::waiver(),
  labels = ggplot2::waiver(),
  max_size = 1,
  default_unit = "cm",
  max = ggplot2::waiver(),
  guide = guide_vector(),
  ...
)

scale_mag_continuous(
  name = ggplot2::waiver(),
  labels = ggplot2::waiver(),
  max_size = 1,
  default_unit = "cm",
  max = ggplot2::waiver(),
  guide = guide_vector(),
  ...
)

Arguments

name	The name of the scale. Used as the axis or legend title. If waiver(), the default, the name of the scale is taken from the first mapping used for that aesthetic. If NULL, the legend title will be omitted.
labels	One of: NULL for no labels waiver() for the default labels computed by the transformation object A character vector giving labels (must be same length as breaks) A function that takes the breaks as input and returns labels as output. Also accepts rlang lambda function notation.
max_size	size of the arrow in centimetres
default_unit	ignored
max	magnitude of the reference arrow in data units. Will be the maximum value if waiver()
guide	type of legend
...	Other arguments passed on to scale_(x|y)_continuous()

Examples

library(ggplot2)
g <- ggplot(seals, aes(long, lat)) +
    geom_vector(aes(dx = delta_long, dy = delta_lat), skip = 2)

g + scale_mag("Seals velocity")

g + scale_mag("Seals velocity", max = 1)

g + scale_mag("Seals velocity", max_size = 2)
g + scale_mag("Seals velocity", default_unit = "mm")