Axis guide with ticks for logarithmic breaks

This axis guide is probably best described as ggplot2::annotation_logticks() but implemented as a guide instead of a geom. The tick marks probably best suit log10 transformations. The function is questioned due to a possible migration of guide functions after ggplot2 releases a new guide system.

Usage

guide_axis_logticks(
  title = waiver(),
  check.overlap = FALSE,
  angle = NULL,
  n.dodge = 1,
  order = 0,
  position = waiver(),
  prescaled = FALSE,
  trunc_lower = NULL,
  trunc_upper = NULL,
  colour = NULL,
  color = NULL,
  base = waiver()
)

Arguments

title

A character string or expression indicating a title of guide. If NULL, the title is not shown. By default (waiver()), the name of the scale object or the name specified in labs() is used for the title.

check.overlap

silently remove overlapping labels, (recursively) prioritizing the first, last, and middle labels.

angle

Compared to setting the angle in theme() / element_text(), this also uses some heuristics to automatically pick the hjust and vjust that you probably want. Can be one of the following:

• NULL to take the angles and hjust/vjust directly from the theme.

• waiver() to allow reasonable defaults in special cases.

• A number representing the text angle in degrees.

n.dodge

The number of rows (for vertical axes) or columns (for horizontal axes) that should be used to render the labels. This is useful for displaying labels that would otherwise overlap.

order

A positive integer of length 1 that specifies the order of this guide among multiple guides. This controls in which order guides are merged if there are multiple guides for the same position. If 0 (default), the order is determined by a secret algorithm.

position

Where this guide should be drawn: one of top, bottom, left, or right.

prescaled

A logical of length one, indicating whether the data has been manually rescaled (TRUE) or the scale takes care of the transformation (FALSE).

trunc_lower, trunc_upper

The lower and upper range of the truncated axis:

• NULL to not perform any truncation.

• A function that takes the break positions as input and returns the lower or upper boundary. Note that also for discrete scales, positions are the mapped positions as numeric.

• A numeric value in data units for the lower and upper boundaries.

• A unit object.

colour, color

A character(1) with a valid colour for colouring the axis text, axis ticks and axis line. Overrules the colour assigned by the theme.

base

When this is provided, the guide takes this as the base for the log transformation instead of trying to guess the base. It is recommended to use this argument if the base is not 10.

Value

An axis_logticks guide class object.

Theme elements

This axis guide uses the following the theme elements:

ggh4x.axis.ticks.length.minor

An rel() object to set the size of minor ticks relative to the length of major ticks (axis.ticks.length). Defaults to rel(2/3).

ggh4x.axis.ticks.length.mini

An rel() object to set the size of smallest ticks, also relative to the length of major ticks (axis.ticks.length). Defaults to rel(1/3).

See also

Other axis-guides: guide_axis_manual(), guide_axis_minor(), guide_axis_nested(), guide_axis_scalebar(), guide_axis_truncated()

Examples

# The guide works well out of the box with log10 scales
p <- ggplot(pressure, aes(temperature, pressure)) +
  geom_line()
p + scale_y_log10(guide = "axis_logticks")


# If the data is already transformed, you can set 'prescaled' to TRUE
ggplot(pressure, aes(temperature, log10(pressure))) +
  geom_line() +
  guides(y = guide_axis_logticks(prescaled = TRUE))
#> Warning: Ignoring unknown argument to `guide_axis_logticks()`: `prescaled`.


# The lenghts of the log-ticks are controlled by the theme relative to the
# major ticks.
p + scale_y_log10(guide = "axis_logticks") +
  theme(
    axis.ticks.length.y = unit(1, "cm"),
    ggh4x.axis.ticks.length.minor = rel(0.55),
    ggh4x.axis.ticks.length.mini = rel(0.1)
  )