windflowOpts: Define 'windflow' options for 'openair' plots

In openair: Tools for the Analysis of Air Pollution Data

Define windflow options for openair plots

Description

This function provides a convenient way to set default options for windflow layers in openair plots, which typically show the mean wind speed and direction as compass arrows. It returns a list of options that can be passed to layer_windflow().

Usage

windflowOpts(
  limits = c(NA, NA),
  range = c(0.1, 1),
  arrow.angle = 15,
  arrow.length = ggplot2::unit(0.5, "lines"),
  arrow.ends = "last",
  arrow.type = "closed",
  lineend = "butt",
  alpha = 1,
  colour = "black",
  linetype = 1,
  linewidth = 0.5,
  color = NULL,
  windflow = TRUE
)

Arguments

limits	Numeric vector of length 2 specifying the limits for wind speed. By default, it is set to c(NA, NA), which means the limits will be determined automatically based on the data.
range	Numeric vector of length 2 specifying the range of possible sizes of the windflow arrows. The default is broadly appropriate throughout openair, but if plots are beings saved at different resolutions it may be appropriate to to tweak this.
arrow.angle, arrow.length, arrow.ends, arrow.type	Passed to the respective arguments of grid::arrow(); used to control various arrow styling options.
lineend	The style of line endings. Options include "butt", "round", and "square". Default is "butt".
alpha	Numeric value between 0 and 1 specifying the transparency of the lines. Default is 1 (fully opaque).
colour, color	Colour of the lines. Default is "black". colour and color are interchangeable, but colour is used preferentially if both are given.
linetype	Line type. Can be an integer (e.g., 1 for solid, 2 for dashed) or a string (e.g., "solid", "dashed"). Default is 1 (solid).
linewidth	Numeric value specifying the width of the lines. Default is 0.5.
windflow	Logical value indicating whether to include the windflow layer. Default is TRUE. Used internally by openair functions.
arrow	A grid::arrow() object specifying the appearance of the arrows.

Value

A list of options that can be passed to the windflow argument of functions like trendLevel().

Examples

# `windflow` can be `TRUE` to use defaults
trendLevel(mydata, type = "default", cols = "greyscale", windflow = TRUE)

# use the `windflowOpts()` function to customise arrows
trendLevel(
  mydata,
  type = "default",
  cols = "greyscale",
  windflow = windflowOpts(
    colour = "white",
    alpha = 0.8,
    linewidth = 0.25,
    linetype = 2
  )
)

openair documentation built on April 2, 2026, 9:07 a.m.