Plot a Vector or Stream Field from a 2D Vector-Valued Function

geom_function_2d_2d() evaluates a user-defined vector field \(\mathbf{F}(x,y) = (dx, dy)\) on a grid and renders it as either a vector field (short arrows at each grid point, the default) or a stream field (integral curves). It wraps ggvfields::geom_vector_field() for type = "vector" and ggvfields::geom_stream_field() for type = "stream".

Usage

geom_function_2d_2d(
  mapping = NULL,
  data = NULL,
  position = "identity",
  ...,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = FALSE,
  fun,
  xlim = NULL,
  ylim = NULL,
  n = 11,
  args = list(),
  type = "vector",
  center = TRUE,
  normalize = TRUE,
  tail_point = FALSE,
  eval_point = FALSE,
  grid = NULL,
  arrow = grid::arrow(angle = 30, length = grid::unit(0.02, "npc"), type = "closed"),
  max_it = 1000,
  T = NULL,
  L = NULL,
  method = "rk4"
)

stat_function_2d_2d(
  mapping = NULL,
  data = NULL,
  geom = ggvfields::GeomStream,
  position = "identity",
  ...,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE,
  fun,
  xlim = NULL,
  ylim = NULL,
  n = 11,
  args = list(),
  max_it = 1000,
  T = NULL,
  L = NULL,
  center = TRUE,
  normalize = TRUE,
  tail_point = FALSE,
  eval_point = FALSE,
  grid = NULL,
  method = "rk4",
  arrow = grid::arrow(angle = 30, length = grid::unit(0.02, "npc"), type = "closed")
)

Arguments

mapping

Set of aesthetic mappings created by aes(). If specified and inherit.aes = TRUE (the default), it is combined with the default mapping at the top level of the plot. You must supply mapping if there is no plot mapping.

data

The data to be displayed in this layer. There are three options:

NULL (default): the data is inherited from the plot data as specified in the call to ggplot().
A data.frame, or other object, will override the plot data. All objects will be fortified to produce a data frame. See fortify() for which variables will be created.
A function will be called with a single argument, the plot data. The return value must be a data.frame, and will be used as the layer data. A function can be created from a formula (e.g. ~ head(.x, 10)).

position

A position adjustment to use on the data for this layer. This can be used in various ways, including to prevent overplotting and improving the display. The position argument accepts the following:

The result of calling a position function, such as position_jitter(). This method allows for passing extra arguments to the position.
A string naming the position adjustment. To give the position as a string, strip the function name of the position_ prefix. For example, to use position_jitter(), give the position as "jitter".
For more information and other ways to specify the position, see the layer position documentation.

...

Other arguments passed to ggplot2::layer().

na.rm

If FALSE, the default, missing values are removed with a warning. If TRUE, missing values are silently removed.

show.legend

Logical. Should this layer be included in the legends? NA, the default, includes if any aesthetics are mapped. FALSE never includes, and TRUE always includes. It can also be a named logical vector to finely select the aesthetics to display. To include legend keys for all levels, even when no data exists, use TRUE. If NA, all levels are shown in legend, but unobserved levels are omitted.

inherit.aes

If FALSE, overrides the default aesthetics, rather than combining with them. This is most useful for helper functions that define both data and aesthetics and shouldn't inherit behaviour from the default plot specification, e.g. annotation_borders().

fun

A function accepting a length-2 numeric vector and returning a length-2 numeric vector \((dx, dy)\).

xlim, ylim

Numeric vectors of length 2 specifying the domain limits. Default to \(c(-1, 1)\).

n

Integer or two-element integer vector. Number of seed points along each axis. Defaults to 11.

args

A named list of additional arguments passed to fun.

type

Character. Either "vector" (default) for short arrows at each grid point, or "stream" for full integral-curve streamlines.

center

Logical. If TRUE (default), centers each arrow/streamline on its seed point.

normalize

Logical. If TRUE (default), normalizes arrow/streamline lengths relative to grid spacing.

tail_point

Logical. If TRUE, draws a point at the tail of each arrow or streamline. Defaults to FALSE.

eval_point

Logical. If TRUE, draws a point at the seed point. Defaults to FALSE.

grid

A data frame of precomputed seed points. If NULL (default), a regular grid is generated from xlim, ylim, and n.

arrow

A grid::arrow() specification. Defaults to a closed arrow at 30° with length 0.02 npc.

max_it

Integer. Maximum integration steps per streamline (type = "stream" only). Defaults to 1000.

T

Numeric. Maximum integration time (type = "stream" only).

L

Numeric. Maximum arc length (type = "stream" only, when normalize = TRUE).

method

Character. Integration method, e.g. "rk4" or "euler" (type = "stream" only). Defaults to "rk4".

geom

The geometric object to use to display the data. Defaults to ggvfields::GeomStream.

Value

A ggplot2 layer.

Examples

library(ggfunction)
f <- function(u) c(-u[2], u[1])

# Vector field (default)
ggplot() + geom_function_2d_2d(fun = f, xlim = c(-1, 1), ylim = c(-1, 1))


# Stream field
ggplot() + geom_function_2d_2d(fun = f, xlim = c(-1, 1), ylim = c(-1, 1),
  type = "stream")

Plot a Vector or Stream Field from a 2D Vector-Valued Function

Usage

Arguments

Value

See also

Examples