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Continuous scale for the pictogram value aesthetic

Source: R/scale-value.R
scale_value_continuous.Rd

scale_value_continuous() registers value (as mapped in geom_pictogram()) as a real trained aesthetic, purely so it can carry a default guide (see guide_pictogram()). It never rescales value itself: symbol_value slot counts need the real data value, so the palette is the identity function.

Usage

scale_value_continuous(
  name = ggplot2::waiver(),
  breaks = ggplot2::waiver(),
  labels = ggplot2::waiver(),
  limits = NULL,
  guide = "pictogram",
  ...
)

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.

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 (e.g., a function returned by scales::extended_breaks()). Note that for position scales, limits are provided after scale expansion. Also accepts rlang lambda function notation.

labels

One of the options below. Please note that when labels is a vector, it is highly recommended to also set the breaks argument as a vector to protect against unintended mismatches.

  • 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)

  • An expression vector (must be the same length as breaks). See ?plotmath for details.

  • A function that takes the breaks as input and returns labels as output. Also accepts rlang lambda function notation.

limits

One of:

  • NULL to use the default scale range

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

  • A function that accepts the existing (automatic) limits and returns new limits. Also accepts rlang lambda function notation. Note that setting limits on positional scales will remove data outside of the limits. If the purpose is to zoom, use the limit argument in the coordinate system (see coord_cartesian()).

guide

The value legend's guide; defaults to guide_pictogram(). Set to "none" (or pass show.legend = FALSE to geom_pictogram()) to hide it.

...

Arguments passed on to continuous_scale

minor_breaks

One of:

  • NULL for no minor breaks

  • waiver() for the default breaks (none for discrete, one minor break between each major break for continuous)

  • A numeric vector of positions

  • A function that given the limits returns a vector of minor breaks. Also accepts rlang lambda function notation. When the function has two arguments, it will be given the limits and major break positions.

oob

One of:

  • Function that handles limits outside of the scale limits (out of bounds). Also accepts rlang lambda function notation.

  • The default (scales::censor()) replaces out of bounds values with NA.

  • scales::squish() for squishing out of bounds values into range.

  • scales::squish_infinite() for squishing infinite values into range.

na.value

Missing values will be replaced with this value.

call

The call used to construct the scale for reporting messages.

super

The super class to use for the constructed scale

Value

A ggplot2 scale.

Details

Picked up automatically for aes(value = ...), so most plots never need to call it directly. Exported for overriding guide or setting explicit breaks.

See also

guide_pictogram(), geom_pictogram()

Examples

library(ggplot2)

# bundled placeholder shapes; a real pack (e.g. icons::fontawesome) works the same
shapes <- icons::icon_set(system.file("icons", package = "ggicons"))

# applied automatically; shown explicitly here just to relabel the legend
ggplot(NULL, aes(x = "Proportion", value = 37)) +
  geom_pictogram(icon = shapes$square, n = 100, nrow = 10) +
  scale_value_continuous(name = "%")
#> Error in geom_pictogram(icon = shapes$square, n = 100, nrow = 10): Problem while converting geom to grob.
#> ℹ Error occurred in the 1st layer.
#> Caused by error in `loadNamespace()`:
#> ! there is no package called ‘grImport2’