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Manual position scales

Source: R/scale_manual.R
scale_x_manual.Rd

[Experimental]

scale_x_manual() and scale_y_manual() are hybrid discrete and continuous position scales for the x and y aesthetics. These accept input like discrete scales, but may map these discrete values to continuous values that needn't be equally spaced.

Usage

scale_x_manual(values, c_limits = NULL, position = "bottom", ...)

scale_y_manual(values, c_limits = NULL, position = "left", ...)

Arguments

values

A numeric vector with the same length as unique values. Alternatively, a function that accepts the limits (unique values) as determined from the data and returns a numeric vector parallel to the input.

c_limits

Either NULL (default) to accept the range of values as the continuous limits, or a numeric(2) to set custom continuous limits.

position

For position scales, The position of the axis. left or right for y axes, top or bottom for x axes.

...

Arguments passed on to ggplot2::discrete_scale

scale_name

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

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 (the scale limits)

  • A character vector of breaks

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

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)

  • 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 values

  • A character vector that defines possible values of the scale and their order

  • A function that accepts the existing (automatic) values and returns new ones. Also accepts rlang lambda function notation.

expand

For position scales, a 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 expansion() 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.

na.translate

Unlike continuous scales, discrete scales can easily show missing values, and do so by default. If you want to remove missing values from a discrete scale, specify na.translate = FALSE.

na.value

If na.translate = TRUE, what aesthetic value should the missing values be displayed as? Does not apply to position scales where NA is always placed at the far right.

drop

Should unused factor levels be omitted from the scale? The default, TRUE, uses the levels that appear in the data; FALSE includes the levels in the factor. Please note that to display every level in a legend, the layer should use show.legend = TRUE.

guide

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

call

The call used to construct the scale for reporting messages.

super

The super class to use for the constructed scale

Value

A <ScaleManualPosition> object that can be added to a plot.

Details

Many thanks to Constantin Ahlmann-Eltze for discussion and suggesting the adoption of this functionality in ggh4x.

Note

There currently is a known bug wherein a c_limits cannot be applied correctly when that range is within the range of the discrete limits.

See also

sep_discrete()

Examples

# A boxplot with interactions
p <- ggplot(mpg, aes(interaction(year, cyl), displ)) +
  geom_boxplot()

# Manually setting positions
p + scale_x_manual(values = c(1, 2, 4, 6, 7, 9, 10))


# Using a function to separate grouped labels
p + scale_x_manual(values = sep_discrete())


# Expanding the continuous limits
p + scale_x_manual(values = sep_discrete(), c_limits = c(NA, 15))


# Together with grouped axis
p + scale_x_manual(values = sep_discrete(), guide = guide_axis_nested())