Scale threshold

Creates a discrete threshold scale. Threshold scales slice palette or range into length(breaks) + 1 bins, with each break defining the threshold between 2 bins.

Threshold scales can be used to create any discrete scale, using either manual breaks or generated breaks via a transform (e.g. breaks_power(n = 6, exponent = 0.5) for a discrete sqrt scale).

Usage

scale_color_threshold(
  col,
  palette = scales::viridis_pal(),
  na_color = "#000000",
  limits = NULL,
  breaks = 0.5,
  tick_format = format_number,
  col_label = "{.col}",
  legend = TRUE
)

scale_threshold(
  col,
  range = 0:1,
  na_value = 0,
  limits = NULL,
  breaks = 0.5,
  tick_format = format_number,
  col_label = "{.col}",
  legend = TRUE
)

Arguments

col

<name | string> The name of the column containing data to be scaled. Must be a valid input to rlang::ensym(); either a named column (non-standard evaluation), a string. Supports tidy-eval.

palette

<color|function> The colour palette of the colour scale. Must be a:

vector of RGBA hex colours,
a palette generator function, taking a length parameter, or
a palette ramp created from scales::colour_ramp()

A scales::colour_ramp() interpolator is created from the input palette.

na_color

<color> The colour value for NA input values.

limits

<c(min, max)> The limits of the scale's input. If NULL, limits are computed from layer data. Values outside the range of limits are clamped.

breaks

<numeric | function> The threshold breaks of the scale. The scale palette or numeric range are linearly interpolated (by length) and mapped onto breaks. Breaks outside the limits of the scale are discarded.

If not NULL, breaks must be either:

a numeric vector
a breaks function, taking a numeric vector argument (e.g. breaks_linear())

Breaks must be in increasing order. Each break will be present on the legend for colour scales.

tick_format

<function> A label function taking a vector of ticks returning formatted ticks.

col_label

<string | function> A template string or a label function for customising the column name in the legend.

if col_label is a string, {.col} may be used to represent the col name
if col_label is a function, the function must take a single argument: the col name

legend

<boolean> Indicate whether the legend should be displayed for this scale.

range

<numeric> The output range of the numeric scale. Must be length >= 2. A stats::approxfun() interpolator is created from the input range.

na_value

<number> The output value for NA input values.

Note

Threshold scales don't require limits, but breaks_trans() does.

Usage

Arguments

Note

See also