Axis with logarithmic tick marks

This axis guide replaces the placement of ticks marks at intervals in log10 space.

Usage

guide_axis_logticks(
  long = 2.25,
  mid = 1.5,
  short = 0.75,
  prescale.base = NULL,
  negative.small = NULL,
  short.theme = element_line(),
  expanded = TRUE,
  cap = "none",
  theme = NULL,
  prescale_base = deprecated(),
  negative_small = deprecated(),
  short_theme = deprecated(),
  ...
)

Arguments

long, mid, short

A grid::unit() object or rel() object setting the (relative) length of the long, middle and short ticks. Numeric values are interpreted as rel() objects. The rel() values are used to multiply values of the axis.ticks.length theme setting.

prescale.base

Base of logarithm used to transform data manually. The default, NULL, will use the scale transformation to calculate positions. Only set prescale.base if the data has already been log-transformed. When using a log-transform in the position scale or in coord_transform(), keep the default NULL argument.

negative.small

When the scale limits include 0 or negative numbers, what should be the smallest absolute value that is marked with a tick? If NULL (default), will be the smallest of 0.1 or 0.1 times the absolute scale maximum.

short.theme

A theme element for customising the display of the shortest ticks. Must be a line or blank element, and it inherits from the axis.minor.ticks setting for the relevant position.

expanded

Whether the ticks should cover the range after scale expansion (TRUE, default), or be restricted to the scale limits (FALSE).

cap

A character to cut the axis line back to the last breaks. Can be "none" (default) to draw the axis line along the whole panel, or "upper" and "lower" to draw the axis to the upper or lower break, or "both" to only draw the line in between the most extreme breaks. TRUE and FALSE are shorthand for "both" and "none" respectively.

theme

A theme object to style the guide individually or differently from the plot's theme settings. The theme argument in the guide partially overrides, and is combined with, the plot's theme.

prescale_base, negative_small, short_theme

...

Arguments passed on to guide_axis

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.

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.

Examples

# A standard plot
p <- ggplot(msleep, aes(bodywt, brainwt)) +
  geom_point(na.rm = TRUE)

# The logticks axis works well with log scales
p + scale_x_log10(guide = "axis_logticks") +
  scale_y_log10(guide = "axis_logticks")


# Or with log-transformed coordinates
p + coord_transform(x = "log10", y = "log10") +
  guides(x = "axis_logticks", y = "axis_logticks")


# When data is transformed manually, one should provide `prescale.base`
# Keep in mind that this axis uses log10 space for placement, not log2
p + aes(x = log2(bodywt), y = log10(brainwt)) +
  guides(
    x = guide_axis_logticks(prescale.base = 2),
    y = guide_axis_logticks(prescale.base = 10)
  )


# A plot with both positive and negative extremes, pseudo-log transformed
set.seed(42)
p2 <- ggplot(data.frame(x = rcauchy(1000)), aes(x = x)) +
  geom_density() +
  scale_x_continuous(
    breaks = c(-10^(4:0), 0, 10^(0:4)),
    transform = "pseudo_log"
  )

# The log ticks are mirrored when 0 is included
p2 + guides(x = "axis_logticks")


# To control the tick density around 0, one can set `negative.small`
p2 + guides(x = guide_axis_logticks(negative.small = 1))