`grid.pattern_wave()`

draws a wave pattern onto the graphic device.

## Usage

```
grid.pattern_wave(
x = c(0, 0, 1, 1),
y = c(1, 0, 0, 1),
id = 1L,
...,
colour = gp$col %||% "grey20",
fill = gp$fill %||% "grey80",
angle = 30,
density = 0.2,
spacing = 0.05,
xoffset = 0,
yoffset = 0,
units = "snpc",
amplitude = 0.5 * spacing,
frequency = 1/spacing,
alpha = gp$alpha %||% NA_real_,
linetype = gp$lty %||% 1,
linewidth = size %||% gp$lwd %||% 1,
size = NULL,
grid = "square",
type = "triangle",
default.units = "npc",
name = NULL,
gp = gpar(),
draw = TRUE,
vp = NULL
)
```

## Arguments

- x
A numeric vector or unit object specifying x-locations of the pattern boundary.

- y
A numeric vector or unit object specifying y-locations of the pattern boundary.

- id
A numeric vector used to separate locations in x, y into multiple boundaries. All locations within the same

`id`

belong to the same boundary.- ...
Currently ignored.

- colour
Stroke colour(s).

- fill
Fill colour(s) or

`grid::pattern()`

/ gradient object(s).- angle
Rotation angle in degrees.

- density
Approx. fraction of area the pattern fills.

- spacing
Spacing between repetitions of pattern (in

`units`

units).- xoffset
Shift pattern along x axis (in

`units`

units).- yoffset
Shift pattern along y axis (in

`units`

units).- units
`grid::unit()`

units for`amplitude`

,`frequency`

,`spacing`

,`xoffset`

, and`yoffset`

parameters.- amplitude
Wave amplitude (in

`units`

units)- frequency
Linear frequency (in inverse

`units`

units)- alpha
Alpha (between 0 and 1) or

`NA`

(default, preserves colors' alpha value).- linetype
Stroke linetype.

- linewidth
Stroke linewidth.

- size
For backwards compatibility can be used to set

`linewidth`

.- grid
Adjusts placement and density of certain graphical elements.

`"square"`

(default) is a square grid.`"hex"`

is a hexagonal grid suitable for hexagonal and triangular tiling.`"hex_circle"`

is a hexagonal grid suitable for circle packing.`"elongated_triangle"`

is a grid used for the "elongated triangle" tiling.- type
Either “sine” or “triangle” (default).

- default.units
A string indicating the default units to use if

`x`

or`y`

are only given as numeric vectors.- name
A character identifier.

- gp
An object of class

`"gpar"`

, typically the output from a call to the function`gpar`

. This is basically a list of graphical parameter settings.- draw
A logical value indicating whether graphics output should be produced.

- vp
A Grid viewport object (or NULL).

## Value

A grid grob object invisibly. If `draw`

is `TRUE`

then also draws to the graphic device as a side effect.

## See also

Use `grid.pattern_stripe()`

for straight lines instead of waves.

## Examples

```
x_hex <- 0.5 + 0.5 * cos(seq(2 * pi / 4, by = 2 * pi / 6, length.out = 6))
y_hex <- 0.5 + 0.5 * sin(seq(2 * pi / 4, by = 2 * pi / 6, length.out = 6))
grid::grid.newpage()
grid.pattern_wave(x_hex, y_hex, colour = "black", type = "sine",
fill = c("red", "blue"), density = 0.4,
spacing = 0.15, angle = 0,
amplitude = 0.05, frequency = 1 / 0.20)
# zig-zag pattern is a wave of `type` "triangle"
grid::grid.newpage()
grid.pattern_wave(x_hex, y_hex, colour = "black", type = "triangle",
fill = c("red", "blue"), density = 0.4,
spacing = 0.15, angle = 0, amplitude = 0.075)
```