Help for package ggarrow

Title:

Arrows for 'ggplot2'

Version:

0.1.1

Description:

A 'ggplot2' extension that adds specialised arrow geometry layers. It offers more arrow options than the standard 'grid' arrows that are built-in many line-based geom layers.

License:

MIT + file LICENSE

Encoding:

UTF-8

RoxygenNote:

7.3.3

Depends:

ggplot2 (≥ 3.5.0)

Imports:

cli, grid, polyclip, rlang (≥ 1.1.0), S7, scales, utils, vctrs

Suggests:

covr, knitr, rmarkdown, testthat (≥ 3.0.0), vdiffr

Config/testthat/edition:

VignetteBuilder:

knitr

URL:

https://teunbrand.github.io/ggarrow/, https://github.com/teunbrand/ggarrow

BugReports:

https://github.com/teunbrand/ggarrow/issues

NeedsCompilation:

Packaged:

2025-09-14 13:03:09 UTC; Teun

Author:

Teun van den Brand

[aut, cre]

Maintainer:

Teun van den Brand <tahvdbrand@gmail.com>

Repository:

CRAN

Date/Publication:

2025-09-14 13:30:02 UTC

ggarrow: Arrows for 'ggplot2'

Description

A 'ggplot2' extension that adds specialised arrow geometry layers. It offers more arrow options than the standard 'grid' arrows that are built-in many line-based geom layers.

Author(s)

Maintainer: Teun van den Brand tahvdbrand@gmail.com (ORCID)

ggarrow extensions to ggplot2

Description

ggarrow relieas on the extension mechanism of ggplot2 through ggproto class objects, that allow for cross-package inheritance of geoms. These objects can be ignored by users for the purpose of making plots, since interacting with these objects is preferred through various ⁠geom_*()⁠ functions.

Arrow annotation layer

Description

This function mirrors annotate() with the following changes. First, the geom argument is pre-populated with "arrow". Second, several parameters from ggarrow are special-cased, because no warning needs to be issued when they don't have length 1.

Usage

annotate_arrow(
  geom = "arrow",
  x = NULL,
  y = NULL,
  xmin = NULL,
  xmax = NULL,
  ymin = NULL,
  ymax = NULL,
  xend = NULL,
  yend = NULL,
  ...,
  na.rm = FALSE
)

Arguments

geom

name of geom to use for annotation

x, y, xmin, ymin, xmax, ymax, xend, yend

Positioning aesthetics. At least one of these must be specified.

...

Other arguments passed on to layer()'s params argument. These arguments broadly fall into one of 4 categories below. Notably, further arguments to the position argument, or aesthetics that are required can not be passed through .... Unknown arguments that are not part of the 4 categories below are ignored.

Static aesthetics that are not mapped to a scale, but are at a fixed value and apply to the layer as a whole. For example, colour = "red" or linewidth = 3. The geom's documentation has an Aesthetics section that lists the available options. The 'required' aesthetics cannot be passed on to the params. Please note that while passing unmapped aesthetics as vectors is technically possible, the order and required length is not guaranteed to be parallel to the input data.
When constructing a layer using a ⁠stat_*()⁠ function, the ... argument can be used to pass on parameters to the geom part of the layer. An example of this is stat_density(geom = "area", outline.type = "both"). The geom's documentation lists which parameters it can accept.
Inversely, when constructing a layer using a ⁠geom_*()⁠ function, the ... argument can be used to pass on parameters to the stat part of the layer. An example of this is geom_area(stat = "density", adjust = 0.5). The stat's documentation lists which parameters it can accept.
The key_glyph argument of layer() may also be passed on through .... This can be one of the functions described as key glyphs, to change the display of the layer in the legend.

na.rm

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

Value

A ⁠<Layer>⁠ ggproto object that can be added to a plot.

Examples

# Annotate an arrow
ggplot() +
  annotate_arrow(
    x = c(0, 1), y = c(0, 1),
    arrow_head = arrow_head_line(),
    arrow_fins = arrow_fins_line(),
    length_head = unit(5, "mm"),
    length_fins = unit(5, "mm")
  )

# Still works with other geoms as well
ggplot(mtcars, aes(x = wt, y = mpg)) + geom_point() +
  annotate_arrow("text", x = 4, y = 25, label = "Some text")

Arrow ornament functions

Description

There are two types of arrow ornament functions: functions for arrow heads, and functions for arrow fins. The heads and fins can be used interchangeably, but the name makes it clearer what is suitable.

Usage

arrow_head_wings(offset = 20, inset = 30)

arrow_fins_feather(indent = 0.3, outdent = indent, height = 0.5)

arrow_head_line(angle = 30, lineend = "butt")

arrow_fins_line(angle = 30, lineend = "butt")

arrow_cup(lineend = "round", angle = NULL)

arrow_head_minimal(angle = 45)

arrow_fins_minimal(angle = 45)

Arguments

offset, angle

A numeric(1) giving an angle in degrees for the angle between the line and tip.

inset

A numeric(1) giving an angle in degrees for the angle inside the tip of the arrowhead.

indent, outdent

A numeric(1) giving the fraction of the feather feather length to offset the notch and the end respectively.

height

A numeric(1) ratio between the length of the feathers and the height of the feathers.

lineend

A character(1), one of "butt", "square", "round" or "parallel". For arrow_cup(), only "butt" and "round" are allowed.

Details

The convention for these functions is that the arrow shaft is fused to the ornament at the (0,0) point and the ornaments ends at the (1,0) point.

Value

A ⁠<matrix[n, 2]>⁠ with x and y columns describing a polygon. It has a notch_angle attribute that is used fusing the fins/head to the shaft of the arrow. They can be given to an arrow plotting function.

Functions

arrow_head_wings(): Places two triangles at either side of the line. Let ABC be a triangle, where A is at the end of the line, B is on the line and C is the arrow wingtip. Then offset is the angle at corner A and inset is the angle at corner C.
arrow_fins_feather(): Places trapezoids at either side of the line. Let ABCD be a quadrilateral shape, where A is at the end of the line, B is on the line, and CD is parallel to AB, but offset from the line. Then, indent is the distance along the line between A and D and outdent is the distance along the line between B and C.
arrow_head_line(): A line as an arrow head.
arrow_fins_line(): A line as an arrow fin.
arrow_cup(): A curved line some fixed distance away from the point to be resected, resembling a 'cup' shape.
arrow_head_minimal(): This is a 'fake' arrow head who in practice doesn't draw anything, but sets the notch_angle attribute such that the arrow shaft is whittled into a triangular point.
arrow_fins_minimal(): This is a 'fake' arrow head who in practise doesn't draw anything, but sets the notch_angle attribute such that a triangle is taken out of the arrow shaft.

Examples

# Plotting winged head
plot(c(-0.5, 1), c(-0.6, 0.6), type = "n")
polygon(arrow_head_wings(), col = "gray")

# Plotting feather fins
plot(c(0, 1), c(-0.25, 0.25), type = "n")
polygon(arrow_fins_feather(), col = "gray")

Continuous arrow scales

Description

These scales can map continuous input to an argument of an arrow generator. The arrow head, arrow fins and middle arrows have separate scales and by default use different generators.

Usage

scale_arrow_head_continuous(
  name = waiver(),
  breaks = waiver(),
  labels = waiver(),
  limits = NULL,
  generator = arrow_head_wings,
  map_arg = "offset",
  other_args = list(),
  range = c(10, 80),
  transform = "identity",
  guide = "legend"
)

scale_arrow_fins_continuous(
  name = waiver(),
  breaks = waiver(),
  labels = waiver(),
  limits = NULL,
  generator = arrow_fins_feather,
  map_arg = "indent",
  other_args = list(),
  range = c(0, 1),
  transform = "identity",
  guide = "legend"
)

scale_arrow_mid_continuous(
  name = waiver(),
  breaks = waiver(),
  labels = waiver(),
  limits = NULL,
  generator = arrow_head_wings,
  map_arg = "offset",
  other_args = list(),
  range = c(10, 80),
  transform = "identity",
  guide = "legend"
)

Arguments

name

The name of the scale. Used as the axis or legend title. If waiver(), the default, the name of the scale is taken from the first mapping used for that aesthetic. If NULL, the legend title will be omitted.

breaks

One of:

NULL for no breaks
waiver() for the default breaks computed by the transformation object
A numeric vector of positions
A function that takes the limits as input and returns breaks as output (e.g., a function returned by scales::extended_breaks()). Note that for position scales, limits are provided after scale expansion. Also accepts rlang lambda function notation.

labels

One of the options below. Please note that when labels is a vector, it is highly recommended to also set the breaks argument as a vector to protect against unintended mismatches.

NULL for no labels
waiver() for the default labels computed by the transformation object
A character vector giving labels (must be same length as breaks)
An expression vector (must be the same length as breaks). See ?plotmath for details.
A function that takes the breaks as input and returns labels as output. Also accepts rlang lambda function notation.

limits

One of:

NULL to use the default scale range
A numeric vector of length two providing limits of the scale. Use NA to refer to the existing minimum or maximum
A function that accepts the existing (automatic) limits and returns new limits. Also accepts rlang lambda function notation. Note that setting limits on positional scales will remove data outside of the limits. If the purpose is to zoom, use the limit argument in the coordinate system (see coord_cartesian()).

generator

A ⁠<function>⁠ that can create an arrow ornament, such as ornamentation functions.

map_arg

An argument of the generator function to map input to.

other_args

Additional, fixed, arguments to pass to the generator.

range

The range that generator's map_arg may take

transform

For continuous scales, the name of a transformation object or the object itself. Built-in transformations include "asn", "atanh", "boxcox", "date", "exp", "hms", "identity", "log", "log10", "log1p", "log2", "logit", "modulus", "probability", "probit", "pseudo_log", "reciprocal", "reverse", "sqrt" and "time".

A transformation object bundles together a transform, its inverse, and methods for generating breaks and labels. Transformation objects are defined in the scales package, and are called ⁠transform_<name>⁠. If transformations require arguments, you can call them from the scales package, e.g. scales::transform_boxcox(p = 2). You can create your own transformation with scales::new_transform().

guide

A function used to create a guide or its name. See guides() for more information.

Value

A ⁠<Scale>⁠ that can be added to a plot.

Examples

base <- ggplot(whirlpool(5), aes(x, y, colour = group)) +
  coord_fixed()

p <- base +
  geom_arrow(
    aes(arrow_head = as.integer(group)),
    length_head = 10
  )

# A typical scale
p + scale_arrow_head_continuous()

# Change other arguments passed to the generator
p + scale_arrow_head_continuous(other_args = list(inset = 90))

# Using another argument of the generator
p + scale_arrow_head_continuous(name = "inset",  map_arg = "inset")

# Using a different generator
p + scale_arrow_head_continuous(
  generator = arrow_head_line,
  map_arg = "angle",
  range = c(20, 80)
)

# The same goes for other arrow aesthetics, but the `generator()` might
# differ.
base +
  geom_arrow(
    aes(arrow_fins = as.integer(group), arrow_mid = as.integer(group)),
    length_fins = 10, arrow_head = NULL
  ) +
  scale_arrow_fins_continuous(map_arg = "height", range = c(0.1, 1)) +
  scale_arrow_mid_continuous(map_arg = "inset")

Debug tool for shaft notching

Description

This is a low-level tool to debug the notching of arrow ornaments onto arrow shafts.

Usage

debug_notching(ornament, width = 0.2)

Arguments

ornament

An arrow ornament.

width

A numeric(1) value for the line's width.

Value

A list with x and y elements.

Examples

NULL

Discrete arrow scales

Description

These scales can map discrete input to various sorts of arrow shapes. The arrow head, arrow fins and middle arrows have separate scales.

Usage

scale_arrow_head_discrete(values = NULL, aesthetics = "arrow_head", ...)

scale_arrow_fins_discrete(values = NULL, aesthetics = "arrow_fins", ...)

scale_arrow_mid_discrete(values = NULL, aesthetics = "arrow_mid", ...)

Arguments

values

One of the following:

A ⁠<character>⁠ vector of arrow function names, without the arrow_-prefix, such as "head_wings" or "fins_line".
An unnested ⁠<list>⁠, possibly mixed ⁠<list>⁠, containing any of the following elements:
- A single ⁠<character>⁠ as described above.
- A ⁠<function>⁠ that when called without any arguments produces a 2-column ⁠<matrix>⁠ that can be used as an arrow.
- A 2-column ⁠<matrix>⁠ giving a polygon to use as an arrow.
NULL, which defaults to a built-in palette with a maximum of 3 arrows.

aesthetics

The names of the aesthetics that this scale works with

...

Arguments passed on to ggplot2::discrete_scale

scale_name

The name of the scale that should be used for error messages associated with this scale.

palette

A palette function that when called with a single integer argument (the number of levels in the scale) returns the values that they should take (e.g., scales::pal_hue()).

name

breaks

One of:

NULL for no breaks
waiver() for the default breaks (the scale limits)
A character vector of breaks
A function that takes the limits as input and returns breaks as output. Also accepts rlang lambda function notation.

labels

One of the options below. Please note that when labels is a vector, it is highly recommended to also set the breaks argument as a vector to protect against unintended mismatches.

NULL for no labels
waiver() for the default labels computed by the transformation object
A character vector giving labels (must be same length as breaks)
An expression vector (must be the same length as breaks). See ?plotmath for details.
A function that takes the breaks as input and returns labels as output. Also accepts rlang lambda function notation.

limits

One of:

NULL to use the default scale values
A character vector that defines possible values of the scale and their order
A function that accepts the existing (automatic) values and returns new ones. Also accepts rlang lambda function notation.

expand

For position scales, a vector of range expansion constants used to add some padding around the data to ensure that they are placed some distance away from the axes. Use the convenience function expansion() to generate the values for the expand argument. The defaults are to expand the scale by 5% on each side for continuous variables, and by 0.6 units on each side for discrete variables.

na.translate

Unlike continuous scales, discrete scales can easily show missing values, and do so by default. If you want to remove missing values from a discrete scale, specify na.translate = FALSE.

na.value

If na.translate = TRUE, what aesthetic value should the missing values be displayed as? Does not apply to position scales where NA is always placed at the far right.

drop

Should unused factor levels be omitted from the scale? The default, TRUE, uses the levels that appear in the data; FALSE includes the levels in the factor. Please note that to display every level in a legend, the layer should use show.legend = TRUE.

guide

A function used to create a guide or its name. See guides() for more information.

position

For position scales, The position of the axis. left or right for y axes, top or bottom for x axes.

call

The call used to construct the scale for reporting messages.

super

The super class to use for the constructed scale

Value

A ⁠<Scale>⁠ that can be added to a plot.

Examples

# A standard arrow plot
p <- ggplot(whirlpool(5), aes(x, y, colour = group)) +
  geom_arrow(length_head = 10, length_fins = 10, arrow_head = NULL)

# A character vector naming arrow shapes as arrow head scale
p + aes(arrow_head = group) +
  scale_arrow_head_discrete(values = c(
      "head_wings", "head_line", "head_minimal", "fins_line", "fins_feather"
  ))

# A mixed list with arrows as arrow fins scale
p + aes(arrow_fins = group) +
  scale_arrow_fins_discrete(values = list(
    "head_wings",              # Using a character
    arrow_head_wings(20, 100), # Using an arrow function
    NULL,                      # No arrow
    matrix(c(1, 0, 0, 0, 0.5, -0.5), ncol = 2), # A matrix
    "fins_feather"
  ))

Legend key glyph for arrows

Description

Like any legend key glyphs, this key can be used to display arrows in a legend.

Usage

draw_key_arrow(data, params, size)

Arguments

data

A single row data frame containing the scaled aesthetics to display in this key

params

A list of additional parameters supplied to the geom.

size

Width and height of key in mm.

Value

An ⁠<arrow_path>⁠ grob

Examples

ggplot(mpg, aes(displ, colour = factor(cyl))) +
  geom_density(key_glyph = draw_key_arrow)

Arrow theme element

Description

Using the theme system, draws arrows in places where element_line() are valid theme elements. Note that the default use of element_arrow() does not actually draw an arrow unless one of the arrow_ arguments is set.

Usage

element_arrow(
  colour = NULL,
  linewidth = NULL,
  linewidth_head = NULL,
  linewidth_fins = NULL,
  stroke_colour = NULL,
  stroke_width = NULL,
  arrow_head = NULL,
  arrow_fins = NULL,
  arrow_mid = NULL,
  length = NULL,
  length_head = NULL,
  length_fins = NULL,
  length_mid = NULL,
  resect = NULL,
  resect_head = NULL,
  resect_fins = NULL,
  justify = NULL,
  force_arrow = NULL,
  mid_place = NULL,
  lineend = NULL,
  linejoin = NULL,
  linemitre = NULL,
  inherit.blank = FALSE,
  ...
)

Arguments

colour

The colour of the arrow.

linewidth, linewidth_head, linewidth_fins

The width of the arrow shaft in millimetres. linewidth is the default width, whereas linewidth_head and linewidth_fins can set non-uniform width at the end and start of the line respectively.

stroke_colour

The colour of the arrow outline.

stroke_width

The width of the arrow outlien.

arrow_head, arrow_fins, arrow_mid

Arrow ornament shapes for the arrow head, arrow fins and middle arrows respectively. Can be one of the following: * NULL for not drawing the ornament. * A ⁠<character>⁠ of length 1 naming an ornament constructor without the "arrow_"-prefix, like "head_wings" or "fins_feather". * A 2-column matrix, such as those built by the ornament constructors.

length, length_head, length_fins, length_mid

Determines the size of the arrow ornaments. length sets the default length, whereas length_head, length_fins and length_mid set the lengths of the arrow head, arrow fins or middle arrows respectively. Can be one of the following:

A ⁠<numeric>⁠ to set the ornament size relative to the ⁠linewidth{_\*}⁠ settings.
A <unit> to control the ornament size in an absolute manner. Behaviour of relative units such as "npc" or "null" is undefined.

resect, resect_head, resect_fins

A numeric(1) denoting millimetres or <unit> to set an offset from the start and end points of the line such that the arrow is shortened. resect sets the default offset, whereas resect_head and resect_fins sets these offsets for the end- and start-point respectively.

justify

A numeric(1) between [0-1] to control where the arrow ornaments should be drawn relative to the (resected) path's endpoints. A value of 0 (default) sets the ornament's tips at the path's endpoint, whereas a value of 1 sets the ornament's base at the path's endpoint.

force_arrow

A logical(1) which if TRUE, will draw arrow ornaments even when the path's length is shorter than the arrow heads and fins. If FALSE, such ornaments will be dropped.

mid_place

Sets the location of middle (interior) ornaments when arrow_mid has been provided. Can be one of the following:

A ⁠<numeric>⁠ vector with values between [0-1] to set middle ornaments at relative positions along the arc-length of the (resected) path.
A <unit> to fill a path with ornaments with th provided unit as spacing between one ornament to the next.

lineend

A character(1) setting the style of the line ends without ornaments. Can be "round", "butt" or "square".

linejoin

A character(1) setting the style of path corners. Can be "round", "mitre" or "bevel".

linemitre

A numeric(1) greater than 1 setting the path's mitre limits.

inherit.blank

A logical(1) indicating if this element should inherit the existence of an ⁠<element_blank>⁠ among its parents. If TRUE, the existence of a blank element among its parents will cause this element to be blank as well. If FALSE, any blank parent element will be ignored when calculating final element state.

...

Not currently in use.

Value

An ⁠<element_arrow>⁠ object that can replace ⁠<element_line>⁠ objects in theme().

Examples

# Setting a bunch of arrows all over the theme
ggplot(whirlpool(5), aes(x, y, group = group)) +
  geom_path() +
  theme(
    # Proper arrow with variable width for x-axis line
    axis.line.x = element_arrow(
      arrow_head = "head_wings", linewidth_head = 2, linewidth_fins = 0
    ),
    # Just a variable width line for the y-axis line
    axis.line.y = element_arrow(linewidth_head = 0, linewidth_fins = 5,
                                lineend = "round"),
    # Arrows for the y-axis ticks
    axis.ticks.y = element_arrow(arrow_fins = arrow_head_line(angle = 45)),
    # Variable width lines for the x-axis ticks
    axis.ticks.x = element_arrow(linewidth_head = 3, linewidth_fins = 0),
    axis.ticks.length = unit(0.5, 'cm'),
    # Arrows for major panel grid
    panel.grid.major = element_arrow(
      arrow_head = "head_wings", arrow_fins = "fins_feather", length = 10
    ),
    # Shortened lines for the minor panel grid
    panel.grid.minor = element_arrow(resect = 20)
  )

Arrows

Description

This arrow geom can be used to draw lines adorned with arrow heads or fins. It is useful as an annotation layer to point to or away from other things on the plot. An arrow typically consists of three parts: the arrowhead, the shaft and fins. This geom places arrow heads at the end of a line and fins at the beginning of a line.

Usage

geom_arrow(
  mapping = NULL,
  data = NULL,
  stat = "identity",
  position = "identity",
  ...,
  arrow_head = arrow_head_wings(),
  arrow_fins = NULL,
  arrow_mid = NULL,
  length = 4,
  length_head = NULL,
  length_fins = NULL,
  length_mid = NULL,
  justify = 0,
  force_arrow = FALSE,
  mid_place = 0.5,
  resect = 0,
  resect_head = NULL,
  resect_fins = NULL,
  lineend = "butt",
  linejoin = "round",
  linemitre = 10,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE
)

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:

If NULL, the 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)).

stat

The statistical transformation to use on the data for this layer. When using a ⁠geom_*()⁠ function to construct a layer, the stat argument can be used to override the default coupling between geoms and stats. The stat argument accepts the following:

A Stat ggproto subclass, for example StatCount.
A string naming the stat. To give the stat as a string, strip the function name of the stat_ prefix. For example, to use stat_count(), give the stat as "count".
For more information and other ways to specify the stat, see the layer stat documentation.

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.

...

Static aesthetics that are not mapped to a scale, but are at a fixed value and apply to the layer as a whole. For example, colour = "red" or linewidth = 3. The geom's documentation has an Aesthetics section that lists the available options. The 'required' aesthetics cannot be passed on to the params. Please note that while passing unmapped aesthetics as vectors is technically possible, the order and required length is not guaranteed to be parallel to the input data.
When constructing a layer using a ⁠stat_*()⁠ function, the ... argument can be used to pass on parameters to the geom part of the layer. An example of this is stat_density(geom = "area", outline.type = "both"). The geom's documentation lists which parameters it can accept.
Inversely, when constructing a layer using a ⁠geom_*()⁠ function, the ... argument can be used to pass on parameters to the stat part of the layer. An example of this is geom_area(stat = "density", adjust = 0.5). The stat's documentation lists which parameters it can accept.
The key_glyph argument of layer() may also be passed on through .... This can be one of the functions described as key glyphs, to change the display of the layer in the legend.

arrow_head, arrow_fins, arrow_mid

A function call to one of the arrow ornament functions that can determine the shape of the arrow head, fins or middle (interior) arrows.

length, length_head, length_fins, length_mid

A ⁠<numeric>⁠ to set the ornament size relative to the ⁠linewidth{_\*}⁠ settings.
A <unit> to control the ornament size in an absolute manner. Behaviour of relative units such as "npc" or "null" is undefined.

justify

A numeric(1) between [0-1] to control where the arrows should be drawn relative to the path's endpoints. A value of 0 sets the arrow's tips at the path's end, whereas a value of 1 sets the arrow's base at the path's end.

force_arrow

A logical(1) which, if TRUE an arrow will be drawn even when the length of the arrow is shorter than the arrow heads and fins. If FALSE, will drop such arrows.

mid_place

Sets the location of middle (interior) arrows, when applicable. Can be one of the following:

A numeric vector: with values between [0-1] to set middle arrows at relative positions along the arc-length of a path.
A <unit>: to fill a path with arrows with the provided unit as distance between one arrow to the next.

resect, resect_head, resect_fins

A numeric(1) denoting millimetres or <unit> to shorten the arrow. resect_head shortens the arrow from the arrow head side, whereas resect_fins shortens the arrow from the fins side. Both inherit from resect.

lineend

Line end style (round, butt, square).

linejoin

Line join style (round, mitre, bevel).

linemitre

Line mitre limit (number greater than 1).

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().

Value

A ⁠<Layer>⁠ ggproto object that can be added to a plot.

Aesthetics

geom_arrow() understands the following aesthetics. Required aesthetics are displayed in bold and defaults are displayed for optional aesthetics:

•	`x`
•	`y`
•	`alpha`	→ `NA`
•	`arrow_fins`	→ `NULL`
•	`arrow_head`	→ `NULL`
•	`arrow_mid`	→ `NULL`
•	`colour`	→ via `theme()`
•	`group`	→ inferred
•	`linetype`	→ via `theme()`
•	`linewidth`	→ via `theme()`
•	`resect_fins`	→ `NULL`
•	`resect_head`	→ `NULL`
•	`stroke_colour`	→ via `theme()`
•	`stroke_width`	→ via `theme()`

Learn more about setting these aesthetics in vignette("ggplot2-specs").

Examples

# Setting up a plot
p <- ggplot(whirlpool(), aes(x, y, colour = group)) +
  coord_equal()

# A standard arrow
p + geom_arrow()

# Arrows can have varying linewidths
p + geom_arrow(aes(linewidth = arc))

# You can use `length_head` to decouple arrow-head size from linewidth
p + geom_arrow(aes(linewidth = arc), length_head = unit(10, "mm"))

# The arrow head shape can be controlled with the `arrow_head` argument
p + geom_arrow(arrow_head = arrow_head_line(), length_head = unit(10, "mm"))

# This works similarly for the arrow fins
p + geom_arrow(
  arrow_fins = arrow_fins_feather(),
  length_fins = unit(7, "mm")
)

Arrow chains

Description

An arrow chains connects a set of coordinates with a sequence of arrows. The geom_arrow_chain() function can be useful to connect observations in a directed manner.

Usage

geom_arrow_chain(
  mapping = NULL,
  data = NULL,
  stat = "identity",
  position = "identity",
  ...,
  arrow_head = arrow_head_wings(),
  arrow_fins = NULL,
  arrow_mid = NULL,
  length = 4,
  length_head = NULL,
  length_fins = NULL,
  length_mid = NULL,
  justify = 0,
  force_arrow = FALSE,
  mid_place = 0.5,
  resect = 1,
  resect_head = NULL,
  resect_fins = NULL,
  lineend = "butt",
  linejoin = "round",
  linemitre = 10,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE
)

Arguments

mapping

data

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

If NULL, the 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.

stat

A Stat ggproto subclass, for example StatCount.
A string naming the stat. To give the stat as a string, strip the function name of the stat_ prefix. For example, to use stat_count(), give the stat as "count".
For more information and other ways to specify the stat, see the layer stat documentation.

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.

...

Static aesthetics that are not mapped to a scale, but are at a fixed value and apply to the layer as a whole. For example, colour = "red" or linewidth = 3. The geom's documentation has an Aesthetics section that lists the available options. The 'required' aesthetics cannot be passed on to the params. Please note that while passing unmapped aesthetics as vectors is technically possible, the order and required length is not guaranteed to be parallel to the input data.
When constructing a layer using a ⁠stat_*()⁠ function, the ... argument can be used to pass on parameters to the geom part of the layer. An example of this is stat_density(geom = "area", outline.type = "both"). The geom's documentation lists which parameters it can accept.
Inversely, when constructing a layer using a ⁠geom_*()⁠ function, the ... argument can be used to pass on parameters to the stat part of the layer. An example of this is geom_area(stat = "density", adjust = 0.5). The stat's documentation lists which parameters it can accept.
The key_glyph argument of layer() may also be passed on through .... This can be one of the functions described as key glyphs, to change the display of the layer in the legend.

arrow_head, arrow_fins, arrow_mid

A function call to one of the arrow ornament functions that can determine the shape of the arrow head, fins or middle (interior) arrows.

length, length_head, length_fins, length_mid

A ⁠<numeric>⁠ to set the ornament size relative to the ⁠linewidth{_\*}⁠ settings.
A <unit> to control the ornament size in an absolute manner. Behaviour of relative units such as "npc" or "null" is undefined.

justify

force_arrow

A logical(1) which, if TRUE an arrow will be drawn even when the length of the arrow is shorter than the arrow heads and fins. If FALSE, will drop such arrows.

mid_place

Sets the location of middle (interior) arrows, when applicable. Can be one of the following:

A numeric vector: with values between [0-1] to set middle arrows at relative positions along the arc-length of a path.
A <unit>: to fill a path with arrows with the provided unit as distance between one arrow to the next.

resect, resect_head, resect_fins

lineend

Line end style (round, butt, square).

linejoin

Line join style (round, mitre, bevel).

linemitre

Line mitre limit (number greater than 1).

na.rm

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

show.legend

inherit.aes

Value

A ⁠<Layer>⁠ ggproto object that can be added to a plot.

Aesthetics

geom_arrow_segment() understands the following aesthetics. Required aesthetics are displayed in bold and defaults are displayed for optional aesthetics:

•	`x`
•	`y`
•	`xend` or `yend`
•	`alpha`	→ `NA`
•	`arrow_fins`	→ `NULL`
•	`arrow_head`	→ `NULL`
•	`arrow_mid`	→ `NULL`
•	`colour`	→ via `theme()`
•	`group`	→ inferred
•	`linetype`	→ via `theme()`
•	`linewidth`	→ via `theme()`
•	`linewidth_fins`	→ `NULL`
•	`linewidth_head`	→ `NULL`
•	`resect_fins`	→ `NULL`
•	`resect_head`	→ `NULL`
•	`stroke_colour`	→ via `theme()`
•	`stroke_width`	→ via `theme()`

The linewidth_fins and linewidth_head inherit from linewidth. They can be used to seperately control the start- and end-width.

Learn more about setting these aesthetics in vignette("ggplot2-specs").

Examples

# Setup dummy data
t <- seq(0, 2 * pi, length.out = 11)
l <- rep(c(1, 0.4), length.out = 11)

df <- data.frame(
  x = cos(t) * l,
  y = sin(t) * l,
  size = l + 0.4
)

p <- ggplot(df, aes(x, y, size = size)) +
  geom_point(colour = 2) +
  coord_equal()

# An arrow chains adapts to the `size` aesthetic to go nicely with points
p + geom_arrow_chain()

# Without arrowhead, it is similar to a `type = 'b'` base R plot
p + geom_arrow_chain(arrow_head = NULL)

# To widen the gap, one can increase the `resect` parameter
p + geom_arrow_chain(resect = 5)

# To ignore the points, set `resect` and `size` to 0
p + geom_arrow_chain(size = 0, resect = 0)

# Linewidths will be interpolated across arrows
p + geom_arrow_chain(aes(linewidth = seq_along(x)))

# Alternatively, we can set them seperately for starts and ends
p + geom_arrow_chain(linewidth_fins = 0, linewidth_head = 3)

Curves with arrows

Description

This arrow geom can be used to draw curves from one point to oneanother with arrow heads or fins.

Usage

geom_arrow_curve(
  mapping = NULL,
  data = NULL,
  stat = "identity",
  position = "identity",
  ...,
  curvature = 0.5,
  angle = 90,
  ncp = 5,
  arrow_head = arrow_head_wings(),
  arrow_fins = NULL,
  arrow_mid = NULL,
  length = 4,
  length_head = NULL,
  length_fins = NULL,
  length_mid = NULL,
  justify = 0,
  force_arrow = FALSE,
  mid_place = 0.5,
  resect = 0,
  resect_head = NULL,
  resect_fins = NULL,
  lineend = "butt",
  linejoin = "round",
  linemitre = 10,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE
)

Arguments

mapping

data

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

If NULL, the 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.

stat

A Stat ggproto subclass, for example StatCount.
A string naming the stat. To give the stat as a string, strip the function name of the stat_ prefix. For example, to use stat_count(), give the stat as "count".
For more information and other ways to specify the stat, see the layer stat documentation.

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.

...

Static aesthetics that are not mapped to a scale, but are at a fixed value and apply to the layer as a whole. For example, colour = "red" or linewidth = 3. The geom's documentation has an Aesthetics section that lists the available options. The 'required' aesthetics cannot be passed on to the params. Please note that while passing unmapped aesthetics as vectors is technically possible, the order and required length is not guaranteed to be parallel to the input data.
When constructing a layer using a ⁠stat_*()⁠ function, the ... argument can be used to pass on parameters to the geom part of the layer. An example of this is stat_density(geom = "area", outline.type = "both"). The geom's documentation lists which parameters it can accept.
Inversely, when constructing a layer using a ⁠geom_*()⁠ function, the ... argument can be used to pass on parameters to the stat part of the layer. An example of this is geom_area(stat = "density", adjust = 0.5). The stat's documentation lists which parameters it can accept.
The key_glyph argument of layer() may also be passed on through .... This can be one of the functions described as key glyphs, to change the display of the layer in the legend.

curvature

A numeric value giving the amount of curvature. Negative values produce left-hand curves, positive values produce right-hand curves, and zero produces a straight line.

angle

A numeric value between 0 and 180, giving an amount to skew the control points of the curve. Values less than 90 skew the curve towards the start point and values greater than 90 skew the curve towards the end point.

ncp

The number of control points used to draw the curve. More control points creates a smoother curve.

arrow_head, arrow_fins, arrow_mid

A function call to one of the arrow ornament functions that can determine the shape of the arrow head, fins or middle (interior) arrows.

length, length_head, length_fins, length_mid

A ⁠<numeric>⁠ to set the ornament size relative to the ⁠linewidth{_\*}⁠ settings.
A <unit> to control the ornament size in an absolute manner. Behaviour of relative units such as "npc" or "null" is undefined.

justify

force_arrow

A logical(1) which, if TRUE an arrow will be drawn even when the length of the arrow is shorter than the arrow heads and fins. If FALSE, will drop such arrows.

mid_place

Sets the location of middle (interior) arrows, when applicable. Can be one of the following:

A numeric vector: with values between [0-1] to set middle arrows at relative positions along the arc-length of a path.
A <unit>: to fill a path with arrows with the provided unit as distance between one arrow to the next.

resect, resect_head, resect_fins

lineend

Line end style (round, butt, square).

linejoin

Line join style (round, mitre, bevel).

linemitre

Line mitre limit (number greater than 1).

na.rm

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

show.legend

inherit.aes

Value

A ⁠<Layer>⁠ ggproto object that can be added to a plot.

Aesthetics

geom_arrow() understands the following aesthetics. Required aesthetics are displayed in bold and defaults are displayed for optional aesthetics:

•	`x`
•	`y`
•	`alpha`	→ `NA`
•	`arrow_fins`	→ `NULL`
•	`arrow_head`	→ `NULL`
•	`arrow_mid`	→ `NULL`
•	`colour`	→ via `theme()`
•	`group`	→ inferred
•	`linetype`	→ via `theme()`
•	`linewidth`	→ via `theme()`
•	`resect_fins`	→ `NULL`
•	`resect_head`	→ `NULL`
•	`stroke_colour`	→ via `theme()`
•	`stroke_width`	→ via `theme()`

Learn more about setting these aesthetics in vignette("ggplot2-specs").

Examples

curve_data <- data.frame(
  x1 = c(2.62, 1.835),
  x2 = c(3.57, 5.250),
  y1 = c(21.0, 33.9),
  y2 = c(15.0, 10.4),
  group = c("A", "B")
)

ggplot(mtcars, aes(wt, mpg)) +
  geom_point() +
  geom_arrow_curve(
    aes(x = x1, y = y1, xend = x2, yend = y2,
        colour = group, arrow_head = group),
    data = curve_data,
    curvature = -0.2, length_head = 10
  )

Arrow segments

Description

geom_arrow_segment() draws a straight arrow between points (x, y) and (xend, yend). In contrast to geom_segment(), the xend and yend aesthetics default to x and y respectively, so only one of xend and yend is required.

Usage

geom_arrow_segment(
  mapping = NULL,
  data = NULL,
  stat = "identity",
  position = "identity",
  ...,
  arrow_head = arrow_head_wings(),
  arrow_fins = NULL,
  arrow_mid = NULL,
  length = 4,
  length_head = NULL,
  length_fins = NULL,
  length_mid = NULL,
  justify = 0,
  force_arrow = FALSE,
  mid_place = 0.5,
  resect = 0,
  resect_head = NULL,
  resect_fins = NULL,
  lineend = "butt",
  linejoin = "round",
  linemitre = 10,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE
)

Arguments

mapping

data

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

If NULL, the 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.

stat

A Stat ggproto subclass, for example StatCount.
A string naming the stat. To give the stat as a string, strip the function name of the stat_ prefix. For example, to use stat_count(), give the stat as "count".
For more information and other ways to specify the stat, see the layer stat documentation.

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.

...

Static aesthetics that are not mapped to a scale, but are at a fixed value and apply to the layer as a whole. For example, colour = "red" or linewidth = 3. The geom's documentation has an Aesthetics section that lists the available options. The 'required' aesthetics cannot be passed on to the params. Please note that while passing unmapped aesthetics as vectors is technically possible, the order and required length is not guaranteed to be parallel to the input data.
When constructing a layer using a ⁠stat_*()⁠ function, the ... argument can be used to pass on parameters to the geom part of the layer. An example of this is stat_density(geom = "area", outline.type = "both"). The geom's documentation lists which parameters it can accept.
Inversely, when constructing a layer using a ⁠geom_*()⁠ function, the ... argument can be used to pass on parameters to the stat part of the layer. An example of this is geom_area(stat = "density", adjust = 0.5). The stat's documentation lists which parameters it can accept.
The key_glyph argument of layer() may also be passed on through .... This can be one of the functions described as key glyphs, to change the display of the layer in the legend.

arrow_head, arrow_fins, arrow_mid

A function call to one of the arrow ornament functions that can determine the shape of the arrow head, fins or middle (interior) arrows.

length, length_head, length_fins, length_mid

A ⁠<numeric>⁠ to set the ornament size relative to the ⁠linewidth{_\*}⁠ settings.
A <unit> to control the ornament size in an absolute manner. Behaviour of relative units such as "npc" or "null" is undefined.

justify

force_arrow

A logical(1) which, if TRUE an arrow will be drawn even when the length of the arrow is shorter than the arrow heads and fins. If FALSE, will drop such arrows.

mid_place

Sets the location of middle (interior) arrows, when applicable. Can be one of the following:

A numeric vector: with values between [0-1] to set middle arrows at relative positions along the arc-length of a path.
A <unit>: to fill a path with arrows with the provided unit as distance between one arrow to the next.

resect, resect_head, resect_fins

lineend

Line end style (round, butt, square).

linejoin

Line join style (round, mitre, bevel).

linemitre

Line mitre limit (number greater than 1).

na.rm

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

show.legend

inherit.aes

Value

A ⁠<Layer>⁠ ggproto object that can be added to a plot.

Aesthetics

geom_arrow_segment() understands the following aesthetics. Required aesthetics are displayed in bold and defaults are displayed for optional aesthetics:

•	`x`
•	`y`
•	`xend` or `yend`
•	`alpha`	→ `NA`
•	`arrow_fins`	→ `NULL`
•	`arrow_head`	→ `NULL`
•	`arrow_mid`	→ `NULL`
•	`colour`	→ via `theme()`
•	`group`	→ inferred
•	`linetype`	→ via `theme()`
•	`linewidth`	→ via `theme()`
•	`linewidth_fins`	→ `NULL`
•	`linewidth_head`	→ `NULL`
•	`resect_fins`	→ `NULL`
•	`resect_head`	→ `NULL`
•	`stroke_colour`	→ via `theme()`
•	`stroke_width`	→ via `theme()`

The linewidth_fins and linewidth_head inherit from linewidth. They can be used to seperately control the start- and end-width.

Learn more about setting these aesthetics in vignette("ggplot2-specs").

Examples

# Setup dummy data
set.seed(42)
df <- data.frame(
  x = LETTERS[1:6],
  y = 6:1 + rnorm(6)
)

# We can omit either `xend` or `yend` for this segment geom
p <- ggplot(df, aes(x, y = 0, yend = y, colour = x))
p + geom_arrow_segment()

# We can set the linewidth globally
p + geom_arrow_segment(aes(linewidth = y))

# Or seperately for the head and fins
p + geom_arrow_segment(aes(linewidth_head = y, linewidth_fins = 0))

# We can also place arrows in the middle
p + geom_arrow_segment(
  arrow_mid = arrow_head_line(), mid_place = c(0.33, 0.66),
  arrow_head = NULL # Turn off head
)

Arrow grob

Description

Creates a graphical object that draws arrows. An arrow typically consists of three parts: the arrowhead, the shaft and fins. Relative to how an arrow is drawn from coordinates, these three parts describe the end, middle and beginning of an arrow line.

Usage

grob_arrow(
  x = unit(c(0, 1), "npc"),
  y = unit(c(0, 1), "npc"),
  id = NULL,
  id.lengths = NULL,
  arrow_head = arrow_head_wings(),
  arrow_fins = NULL,
  arrow_mid = NULL,
  length_head = unit(5, "mm"),
  length_fins = NULL,
  length_mid = NULL,
  justify = 0,
  shaft_width = unit(1, "mm"),
  mid_place = 0.5,
  resect = unit(0, "mm"),
  resect_fins = NULL,
  resect_head = NULL,
  force_arrow = FALSE,
  default.units = "mm",
  name = NULL,
  gp = gpar(),
  vp = NULL
)

Arguments

x

A numeric vector or unit object specifying x-values.

y

A numeric vector or unit object specifying y-values.

id

A numeric vector used to separate locations in x and y into multiple lines. All locations with the same id belong to the same line.

id.lengths

A numeric vector used to separate locations in x and y into multiple lines. Specifies consecutive blocks of locations which make up separate lines.

arrow_head, arrow_fins, arrow_mid

A ⁠<matrix[n, 2]>⁠, such as those returned by arrow ornament functions, giving arrow shapes. The matrix can (should) have the notch_angle attribute that will be used to fuse the shaft to the arrow ornaments. If NULL, no ornament will be drawn.

length_head, length_fins, length_mid

A <unit> object controlling the size of the arrow ornaments.

justify

shaft_width

A <unit> object controlling the width of the arrow's shaft.

mid_place

Sets the location of middle (interior) arrows, when applicable. Can be one of the following:

A numeric vector: with values between [0-1] to set middle arrows at relative positions along the arc-length of a path.
A <unit>: to fill a path with arrows with the provided unit as distance between one arrow to the next.

resect, resect_fins, resect_head

A <unit> object that can be used to create an offset between the endings of the coordinates and where the arrow will be displayed visually. resect_fins and resect_head control this offset at the start and end of the arrow respectively and both default to resect.

force_arrow

A logical(1) which, if TRUE an arrow will be drawn even when the length of the arrow is shorter than the arrow heads and fins. If FALSE, will drop such arrows.

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.

vp

A Grid viewport object (or NULL).

Value

A ⁠<arrow_path>⁠ graphical object.

Examples

requireNamespace("grid")

# Creating an arrow
arrow <- grob_arrow(
  x = unit(c(0.2, 0.5, 0.8, 0.2, 0.5, 0.8), "npc"),
  y = unit(c(0.2, 0.8, 0.2, 0.8, 0.2, 0.8), "npc"),
  id.lengths  = c(3, 3),
  arrow_head  = arrow_head_wings(),
  arrow_fins  = arrow_fins_feather(),
  length_fins = 8,
  shaft_width = 1,
  gp = grid::gpar(fill = c("dodgerblue", "tomato"), col = "black")
)

# Drawing the arrow
grid::grid.newpage(); grid::grid.draw(arrow)

Arrow curve grob.

Description

Creates a graphical object that draws curved arrows.

Usage

grob_arrow_curve(
  x1,
  y1,
  x2,
  y2,
  default.units = "mm",
  curvature = 1,
  angle = 90,
  ncp = 1,
  shape = 0.5,
  square = TRUE,
  squareShape = 1,
  inflect = FALSE,
  open = TRUE,
  name = NULL,
  gp = gpar(),
  vp = NULL,
  ...,
  width_head = unit(1, "mm"),
  width_fins = unit(1, "mm")
)

Arguments

x1

A numeric vector or unit object specifying the x-location of the start point.

y1

A numeric vector or unit object specifying the y-location of the start point.

x2

A numeric vector or unit object specifying the x-location of the end point.

y2

A numeric vector or unit object specifying the y-location of the end point.

default.units

A string indicating the default units to use if x1, y1, x2 or y2 are only given as numeric values.

curvature

A numeric value giving the amount of curvature. Negative values produce left-hand curves, positive values produce right-hand curves, and zero produces a straight line.

angle

ncp

The number of control points used to draw the curve. More control points creates a smoother curve.

shape

A numeric vector of values between -1 and 1, which control the shape of the curve relative to its control points. See grid.xspline for more details.

square

A logical value that controls whether control points for the curve are created city-block fashion or obliquely. When ncp is 1 and angle is 90, this is typically TRUE, otherwise this should probably be set to FALSE (see Examples below).

squareShape

A shape value to control the behaviour of the curve relative to any additional control point that is inserted if square is TRUE.

inflect

A logical value specifying whether the curve should be cut in half and inverted (see Examples below).

open

A logical value indicating whether to close the curve (connect the start and end points).

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.

vp

A Grid viewport object (or NULL).

...

Arguments passed on to grob_arrow

arrow_head,arrow_fins,arrow_mid

length_head,length_fins,length_mid

A <unit> object controlling the size of the arrow ornaments.

resect,resect_fins,resect_head

force_arrow

A logical(1) which, if TRUE an arrow will be drawn even when the length of the arrow is shorter than the arrow heads and fins. If FALSE, will drop such arrows.

justify

mid_place

Sets the location of middle (interior) arrows, when applicable. Can be one of the following:

A numeric vector: with values between [0-1] to set middle arrows at relative positions along the arc-length of a path.
A <unit>: to fill a path with arrows with the provided unit as distance between one arrow to the next.

x

A numeric vector or unit object specifying x-values.

y

A numeric vector or unit object specifying y-values.

id

A numeric vector used to separate locations in x and y into multiple lines. All locations with the same id belong to the same line.

id.lengths

A numeric vector used to separate locations in x and y into multiple lines. Specifies consecutive blocks of locations which make up separate lines.

width_fins, width_head

A <unit> object controlling the width of the arrow's shaft at the ⁠(x1, y1)⁠ and ⁠(x2, y2)⁠ location respectively.

Value

A ⁠<curve_arrow>⁠ graphical object.

Examples

requireNamespace("grid")

# Creating the curved arrow
grob <- grob_arrow_curve(
  x1 = unit(0.25, "npc"), y1 = unit(0.25, "npc"),
  x2 = unit(0.75, "npc"), y2 = unit(0.75, "npc"),
  angle = 90, curvature = 0.5, ncp = 5,
  arrow_head = arrow_head_line()
)

# Drawing the arrow
grid::grid.newpage(); grid::grid.draw(grob)

Scale for resection

Description

Arrow geoms have a resect aesthetic that controls how much an arrow should be shortened. These scales can help to rescale the output range of resection.

Usage

scale_resect_continuous(
  ...,
  range = NULL,
  aesthetics = c("resect_head", "resect_fins"),
  guide = "none"
)

scale_resect_discrete(
  ...,
  values = NULL,
  aesthetics = c("resect_head", "resect_fins"),
  range = NULL,
  guide = "none"
)

Arguments

...

Arguments passed on to ggplot2::continuous_scale, ggplot2::discrete_scale

name

breaks

One of:

NULL for no breaks
waiver() for the default breaks computed by the transformation object
A numeric vector of positions
A function that takes the limits as input and returns breaks as output (e.g., a function returned by scales::extended_breaks()). Note that for position scales, limits are provided after scale expansion. Also accepts rlang lambda function notation.

minor_breaks

One of:

NULL for no minor breaks
waiver() for the default breaks (none for discrete, one minor break between each major break for continuous)
A numeric vector of positions
A function that given the limits returns a vector of minor breaks. Also accepts rlang lambda function notation. When the function has two arguments, it will be given the limits and major break positions.

n.breaks

An integer guiding the number of major breaks. The algorithm may choose a slightly different number to ensure nice break labels. Will only have an effect if breaks = waiver(). Use NULL to use the default number of breaks given by the transformation.

labels

One of the options below. Please note that when labels is a vector, it is highly recommended to also set the breaks argument as a vector to protect against unintended mismatches.

NULL for no labels
waiver() for the default labels computed by the transformation object
A character vector giving labels (must be same length as breaks)
An expression vector (must be the same length as breaks). See ?plotmath for details.
A function that takes the breaks as input and returns labels as output. Also accepts rlang lambda function notation.

limits

One of:

NULL to use the default scale range
A numeric vector of length two providing limits of the scale. Use NA to refer to the existing minimum or maximum
A function that accepts the existing (automatic) limits and returns new limits. Also accepts rlang lambda function notation. Note that setting limits on positional scales will remove data outside of the limits. If the purpose is to zoom, use the limit argument in the coordinate system (see coord_cartesian()).

rescaler

A function used to scale the input values to the range [0, 1]. This is always scales::rescale(), except for diverging and n colour gradients (i.e., scale_colour_gradient2(), scale_colour_gradientn()). The rescaler is ignored by position scales, which always use scales::rescale(). Also accepts rlang lambda function notation.

oob

One of:

Function that handles limits outside of the scale limits (out of bounds). Also accepts rlang lambda function notation.
The default (scales::censor()) replaces out of bounds values with NA.
scales::squish() for squishing out of bounds values into range.
scales::squish_infinite() for squishing infinite values into range.

expand

na.value

Missing values will be replaced with this value.

transform

trans

Deprecated in favour of transform.

position

For position scales, The position of the axis. left or right for y axes, top or bottom for x axes.

call

The call used to construct the scale for reporting messages.

na.translate

Unlike continuous scales, discrete scales can easily show missing values, and do so by default. If you want to remove missing values from a discrete scale, specify na.translate = FALSE.

drop

range

A numeric vector of length 2 indicating the minimum and maximum size of the resection after transformation in millimetres. range is mutually exclusive with the values argument in discrete scales.

aesthetics

The names of the aesthetics that this scale works with.

guide

A function used to create a guide or its name. See guides() for more information.

values

(Discrete scale only) A numeric vector to map data values to. The values will be matched in order with the limits of the scale, or with breaks if provided. If this is a named vector, the values will be matched based on the names instead. Data values that don't match will be given na.value. values is mutually exclusive with the range

Details

Conceptually, these scales depart slightly from ggplot2 conventions. The scale_resect_continuous() function returns an identity scale when range = NULL (default) and a typical continuous scale when the range argument is set. The scale_resect_discrete() acts as a manual scale when values is set and as an ordinal scale when range is set.

Value

A ⁠<Scale>⁠ that can be added to a plot.

Examples

# A plot with points indicating path ends
p <- ggplot(whirlpool(5), aes(x, y, colour = group)) +
  geom_point(data = ~ subset(.x, arc == ave(arc, group, FUN = max)))

# Resect scale as an identity scale
p + geom_arrow(aes(resect_head = as.integer(group))) +
  scale_resect_continuous()

# Resect scale as typical continuous scale
p + geom_arrow(aes(resect_head = as.integer(group))) +
  scale_resect_continuous(range = c(0, 10))

# Resect scale as manual scale
p + geom_arrow(aes(resect_head = group)) +
  scale_resect_discrete(values = c(10, 5, 0, 5, 10))

# Resect scale as ordinal scale
p + geom_arrow(aes(resect_head = group)) +
  scale_resect_discrete(range = c(0, 10))

Whirlpool data

Description

This function returns some made-up data to test arrow functionality with.

Usage

whirlpool(n = 5, detail = 100)

Arguments

n

The number of streams in the whirlpool.

detail

The number of points per stream.

Value

A data.frame

Examples

whirlpool()

ggarrow: Arrows for 'ggplot2'

Description

Author(s)

See Also

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Arguments

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Description

Usage

Arguments

Value

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Arrow theme element

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Value

Examples

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See Also

Examples

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Description

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Arguments

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See Also

Examples

Curves with arrows

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Usage

Arguments

Value

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See Also

Examples

Arrow segments

Description

Usage

Arguments

Value