Non-positional scales for mixtime data

Source: R/scale-time.R

Beyond x and y, mixtime vectors can also be mapped to colour, fill, alpha, size, and linewidth (e.g. to shade points or lines by when they occurred). These are the default scales used for mixtime vectors mapped to those aesthetics, and are automatically applied. To override the scale's behaviour manually, use scale_*_mixtime.

scale_colour_mixtime(
  name = waiver(),
  ...,
  low = "#132B43",
  high = "#56B1F7",
  space = "Lab",
  na.value = "grey50",
  guide = "colourbar",
  aesthetics = "colour"
)

scale_color_mixtime(
  name = waiver(),
  ...,
  low = "#132B43",
  high = "#56B1F7",
  space = "Lab",
  na.value = "grey50",
  guide = "colourbar",
  aesthetics = "colour"
)

scale_fill_mixtime(
  name = waiver(),
  ...,
  low = "#132B43",
  high = "#56B1F7",
  space = "Lab",
  na.value = "grey50",
  guide = "colourbar",
  aesthetics = "fill"
)

scale_alpha_mixtime(name = waiver(), ..., range = NULL, aesthetics = "alpha")

scale_size_mixtime(name = waiver(), ..., range = NULL, aesthetics = "size")

scale_linewidth_mixtime(
  name = waiver(),
  ...,
  range = NULL,
  aesthetics = "linewidth"
)

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.

...

Arguments passed on to continuous_scale

scale_name

[Deprecated] The name of the scale that should be used for error messages associated with this scale.

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.

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.

n.breaks

An integer guiding the number of major breaks. The algorithm may choose a slightly different number to ensure nice break labels. Will only have an effect if breaks = waiver(). Use NULL to use the default number of breaks given by the transformation.

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()).

rescaler

A function used to scale the input values to the range [0, 1]. This is always scales::rescale(), except for diverging and n colour gradients (i.e., scale_colour_gradient2(), scale_colour_gradientn()). The rescaler is ignored by position scales, which always use scales::rescale(). Also accepts rlang lambda function notation.

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.

trans

[Deprecated] Deprecated in favour of transform.

call

The call used to construct the scale for reporting messages.

super

The super class to use for the constructed scale

low, high

Colours for low and high ends of the gradient.

space

colour space in which to calculate gradient. Must be "Lab" - other values are deprecated.

na.value

Colour to use for missing values

guide

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

aesthetics

The names of the aesthetics that this scale should be applied to, allowing this to be used with a different aesthetic (e.g. a custom aesthetic tied to colour or fill by ggplot2::aes()/ggplot2::register_theme_elements()).

range

Output range for size, alpha, and linewidth, given as a numeric vector of length 2. If NULL, the aesthetic's default range is used.

Details

Unlike scale_x_mixtime() and scale_y_mixtime(), these scales don't draw a common time axis shared by multiple layers, so there is only a single aesthetic column to map. The common chronon (and, for colour/fill, the colour gradient) is still resolved the same way as the position scales, with mixed granularities coerced onto the finest chronon they can all be represented in and time_breaks/time_labels accepted for time-aware breaks and labelling.

Examples

library(ggplot2)
df <- data.frame(
  time = mixtime::yearmonth(600:611),
  value = as.numeric(USAccDeaths[1:12])
)

ggplot(df, aes(value, 1, colour = time)) +
  geom_point(size = 5) +
  scale_colour_mixtime()