R: Arcs based on radius and radians

geom_arc {ggforce} | R Documentation

## Arcs based on radius and radians

### Description

This set of stats and geoms makes it possible to draw circle segments based on a center point, a radius and a start and end angle (in radians). These functions are intended for cartesian coordinate systems and makes it possible to create circular plot types without using the `ggplot2::coord_polar()` coordinate system.

### Usage

    stat_arc(
      mapping = NULL,
      data = NULL,
      geom = "arc",
      position = "identity",
      na.rm = FALSE,
      show.legend = NA,
      n = 360,
      inherit.aes = TRUE,
      ...
    )

    geom_arc(
      mapping = NULL,
      data = NULL,
      stat = "arc",
      position = "identity",
      n = 360,
      arrow = NULL,
      lineend = "butt",
      na.rm = FALSE,
      show.legend = NA,
      inherit.aes = TRUE,
      ...
    )

    stat_arc2(
      mapping = NULL,
      data = NULL,
      geom = "path_interpolate",
      position = "identity",
      na.rm = FALSE,
      show.legend = NA,
      n = 360,
      inherit.aes = TRUE,
      ...
    )

    geom_arc2(
      mapping = NULL,
      data = NULL,
      stat = "arc2",
      position = "identity",
      n = 360,
      arrow = NULL,
      lineend = "butt",
      na.rm = FALSE,
      show.legend = NA,
      inherit.aes = TRUE,
      ...
    )

    stat_arc0(
      mapping = NULL,
      data = NULL,
      geom = "arc0",
      position = "identity",
      na.rm = FALSE,
      show.legend = NA,
      inherit.aes = TRUE,
      ...
    )

    geom_arc0(
      mapping = NULL,
      data = NULL,
      stat = "arc0",
      position = "identity",
      ncp = 5,
      arrow = NULL,
      lineend = "butt",
      na.rm = FALSE,
      show.legend = NA,
      inherit.aes = TRUE,
      ...
    )

### Arguments

`mapping` | Set of aesthetic mappings created by `aes()` or `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)`).
`geom` | The geometric object to use display the data
`position` | Position adjustment, either as a string, or the result of a call to a position adjustment function.
`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.
`n` | the smoothness of the arc. Sets the number of points to use if the arc would cover a full circle
`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. `borders()`.
`...` | Other arguments passed on to `layer()`. These are often aesthetics, used to set an aesthetic to a fixed value, like `colour = "red"` or `size = 3`. They may also be parameters to the paired geom/stat.
`stat` | The statistical transformation to use on the data for this layer, as a string.
`arrow` | Arrow specification, as created by `grid::arrow()`.
`lineend` | Line end style (round, butt, square).
`ncp` | the number of control points used to draw the arc with curveGrob. Determines how well the arc approximates a circle section

### Details

An arc is a segment of a line describing a circle. It is the fundamental visual element in donut charts where the length of the segment (and conversely the angular span of the segment) describes the proportion of an entety.

### Aesthetics

geom_arc understand the following aesthetics (required aesthetics are in bold):

- x0

- y0

- r

- start

- end

- color

- size

- linetype

- alpha

- lineend

### Computed variables

x, y

  The start coordinates for the segment

xend, yend

  The end coordinates for the segment

curvature

  The curvature of the curveGrob to match a circle

### See Also

`geom_arc_bar()` for drawing arcs with fill

### Examples

    # Lets make some data
    arcs <- data.frame(
      start = seq(0, 2 * pi, length.out = 11)[-11],
      end = seq(0, 2 * pi, length.out = 11)[-1],
      r = rep(1:2, 5)
    )

    # Behold the arcs
    ggplot(arcs) +
      geom_arc(aes(x0 = 0, y0 = 0, r = r, start = start, end = end,
                   linetype = factor(r)))

    # Use the calculated index to map values to position on the arc
    ggplot(arcs) +
      geom_arc(aes(x0 = 0, y0 = 0, r = r, start = start, end = end,
                   size = stat(index)), lineend = 'round') +
      scale_radius() # linear size scale

    # The 0 version maps directly to curveGrob instead of calculating the points
    # itself
    ggplot(arcs) +
      geom_arc0(aes(x0 = 0, y0 = 0, r = r, start = start, end = end,
                    linetype = factor(r)))

    # The 2 version allows interpolation of aesthetics between the start and end
    # points
    arcs2 <- data.frame(
      angle = c(arcs$start, arcs$end),
      r = rep(arcs$r, 2),
      group = rep(1:10, 2),
      colour = sample(letters[1:5], 20, TRUE)
    )

    ggplot(arcs2) +
      geom_arc2(aes(x0 = 0, y0 = 0, r = r, end = angle, group = group,
                    colour = colour), size = 2)

[Package ggforce version 0.3.3 Index]