Scales for area or radius

Description

scale_size scales area, scale_radius scales radius. The size aesthetic is most commonly used for points and text, and humans perceive the area of points (not their radius), so this provides for optimal perception. scale_size_area ensures that a value of 0 is mapped to a size of 0.

Usage

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scale_radius(name = waiver(), breaks = waiver(), labels = waiver(),
  limits = NULL, range = c(1, 6), trans = "identity", guide = "legend")

scale_size(name = waiver(), breaks = waiver(), labels = waiver(),
  limits = NULL, range = c(1, 6), trans = "identity", guide = "legend")

scale_size_area(..., max_size = 6)

Arguments

name

The name of the scale. Used as axis or legend title. If NULL, the default, the name of the scale is taken from the first mapping used for that aesthetic.

breaks

One of:

  • NULL for no breaks

  • waiver() for the default breaks computed by the transformation object

  • A numeric vector of positions

  • A function that takes the limits as input and returns breaks as output

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

limits

A numeric vector of length two providing limits of the scale. Use NA to refer to the existing minimum or maximum.

range

a numeric vector of length 2 that specifies the minimum and maximum size of the plotting symbol after transformation.

trans

Either the name of a transformation object, or the object itself. Built-in transformations include "asn", "atanh", "boxcox", "exp", "identity", "log", "log10", "log1p", "log2", "logit", "probability", "probit", "reciprocal", "reverse" and "sqrt".

A transformation object bundles together a transform, it's inverse, and methods for generating breaks and labels. Transformation objects are defined in the scales package, and are called name_trans, e.g. boxcox_trans. You can create your own transformation with trans_new.

guide

Name of guide object, or object itself.

...

Other arguments passed on to continuous_scale to control name, limits, breaks, labels and so forth.

max_size

Size of largest points.

See Also

scale_size_area if you want 0 values to be mapped to points with size 0.

Examples

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p <- ggplot(mpg, aes(displ, hwy, size = hwy)) +
   geom_point()
p
p + scale_size("Highway mpg")
p + scale_size(range = c(0, 10))

# If you want zero value to have zero size, use scale_size_area:
p + scale_size_area()

# This is most useful when size is a count
ggplot(mpg, aes(class, cyl)) +
  geom_count() +
  scale_size_area()

# If you want to map size to radius (usually bad idea), use scale_radius
p + scale_radius()

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