breakOpts: Define 'breaks' options for 'openair' plots

In openair: Tools for the Analysis of Air Pollution Data

Define breaks options for openair plots

Description

This function provides a convenient way to set default options for breaks arguments in openair plots, which cut continuous colour scales into discrete bins.

Usage

breakOpts(
  breaks = NULL,
  labels = NULL,
  method = c("number", "interval", "width", "pretty", "wd"),
  max.bins = NULL,
  include.lowest = NULL,
  right = NULL,
  dig.lab = NULL
)

Arguments

breaks, labels	If a categorical colour scale is required, breaks should be specified. This can be either of: A single value, which will use the strategy specified by method to bin the scale. By default, this uses the same logic as cutData(), which splits the scale into quantiles. A numeric vector, which will define the specific breakpoints. For example, c(0, 50, 100) will bin the data into ⁠0 to 50⁠, ⁠50 to 100⁠, and so on. If breaks does not cover the full range of the data, the outer limits will be extended so that the full colour scale is covered while retaining the desired number of breaks. By default, breaks will generate nicely formatted labels for each category. The labels argument overrides this - for example, a user could define ⁠breaks = 3, labels = c("low", "medium", "high")⁠. Care should be taken to provide the appropriate number of labels - it should always be equal to the number of bins, or one less than the number of breakpoints.
method	When breaks is a single number (e.g., breaks = 5), method controls how this value is used to create breaks. Can be one of: "number" - splits the range into n quantiles (i.e., bins with roughly the same number of measurements in them). This is equivalent to cutData(). "interval" - splits the range into n bins of equal width. "width" - splits the range into some number of bins with width n. "pretty" - splits the range into approximately n bins with aesthetically pleasing breakpoints using pretty(). "wd" - splits the range into wind direction bins by passing it to cutData(). Note that this option requires breaks to be one of 4, 8, 16 or 32 and ignores all other arguments.
max.bins	If max.bins is set, only that number of bins will ever be created. For example, if breaks = c(0, 10, 20, 30, 40, 50) and max.bins = 3, breaks will be set to c(0, 10, 20, 50) to ensure only three bins are made.
include.lowest	logical, indicating if an x[i] equal to the lowest (or highest, for right = FALSE) 'breaks' value should be included.
right	logical, indicating if the intervals should be closed on the right (and open on the left) or vice versa.
dig.lab	Integer which is used when labels are not given. It determines the number of digits used in formatting the break numbers. If NULL, the labels will use the minimum number of decimal places possible to ensure the breakpoints are unique, dropping all trailing zeroes.

openair documentation built on May 20, 2026, 5:07 p.m.