Scales for area or radius

Source: R/scale-size.r

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.

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 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.
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. scales::boxcox_trans(). You can create your own transformation with scales::trans_new().
guide

A function used to create a guide or its name. See guides() for more info.
...

Arguments passed on to continuous_scale

name

The name of the scale. Used as 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.

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

minor_breaks

One of:

  • NULL for no minor breaks

  • waiver() for the default breaks (one minor break between each major break)

  • A numeric vector of positions

  • A function that given the limits returns a vector of minor breaks.

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.

oob

Function that handles limits outside of the scale limits (out of bounds). The default replaces out of bounds values with NA.

na.value

Missing values will be replaced with this value.

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. scales::boxcox_trans(). You can create your own transformation with scales::trans_new().

guide

A function used to create a guide or its name. See guides() for more info.

position

The position of the axis. "left" or "right" for vertical scales, "top" or "bottom" for horizontal scales

super

The super class to use for the constructed scale

expand

Vector of range expansion constants used to add some padding around the data, to ensure that they are placed some distance away from the axes. Use the convenience function expand_scale() to generate the values for the expand argument. The defaults are to expand the scale by 5% on each side for continuous variables, and by 0.6 units on each side for discrete variables.
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

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()