R: Link points with paths

geom_link {ggforce} | R Documentation

## Link points with paths

### Description

This set of geoms makes it possible to connect points using straight lines. Before you think `ggplot2::geom_segment()` and `ggplot2::geom_path()`, these functions have some additional tricks up their sleeves. geom_link connects two points in the same way as `ggplot2::geom_segment()` but does so by interpolating multiple points between the two. An additional column called index is added to the data with a sequential progression of the interpolated points. This can be used to map color or size to the direction of the link. geom_link2 uses the same syntax as `ggplot2::geom_path()` but interpolates between the aesthetics given by each row in the data.

### Usage

    stat_link(
      mapping = NULL,
      data = NULL,
      geom = "path",
      position = "identity",
      na.rm = FALSE,
      show.legend = NA,
      n = 100,
      inherit.aes = TRUE,
      ...
    )

    stat_link2(
      mapping = NULL,
      data = NULL,
      geom = "path_interpolate",
      position = "identity",
      na.rm = FALSE,
      show.legend = NA,
      n = 100,
      inherit.aes = TRUE,
      ...
    )

    geom_link(
      mapping = NULL,
      data = NULL,
      stat = "link",
      position = "identity",
      arrow = NULL,
      lineend = "butt",
      na.rm = FALSE,
      show.legend = NA,
      inherit.aes = TRUE,
      n = 100,
      ...
    )

    geom_link2(
      mapping = NULL,
      data = NULL,
      stat = "link2",
      position = "identity",
      arrow = NULL,
      lineend = "butt",
      na.rm = FALSE,
      show.legend = NA,
      inherit.aes = TRUE,
      n = 100,
      ...
    )

    geom_link0(
      mapping = NULL,
      data = NULL,
      stat = "identity",
      position = "identity",
      ...,
      arrow = NULL,
      arrow.fill = NULL,
      lineend = "butt",
      linejoin = "round",
      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 number of points to create for each segment
`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).
`arrow.fill` | fill colour to use for the arrow head (if closed). `NULL` means use `colour` aesthetic.
`linejoin` | Line join style (round, mitre, bevel).

### Aesthetics

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

- x

- y

- xend

- yend

- color

- size

- linetype

- alpha

- lineend

geom_link2 understand the following aesthetics (required aesthetics are in bold):

- x

- y

- color

- size

- linetype

- alpha

- lineend

### Computed variables

x, y

  The interpolated point coordinates

index

  The progression along the interpolation mapped between 0 and 1

### Examples

    # Lets make some data
    lines <- data.frame(
      x = c(5, 12, 15, 9, 6),
      y = c(17, 20, 4, 15, 5),
      xend = c(19, 17, 2, 9, 5),
      yend = c(10, 18, 7, 12, 1),
      width = c(1, 10, 6, 2, 3),
      colour = letters[1:5]
    )

    ggplot(lines) +
      geom_link(aes(x = x, y = y, xend = xend, yend = yend, colour = colour,
                    alpha = stat(index), size = stat(index)))

    ggplot(lines) +
      geom_link2(aes(x = x, y = y, colour = colour, size = width, group = 1),
                 lineend = 'round', n = 500)

    # geom_link0 is simply an alias for geom_segment to put the link geoms in
    # line with the other line geoms with multiple versions. `index` is not
    # available here
    ggplot(lines) +
      geom_link0(aes(x = x, y = y, xend = xend, yend = yend, colour = colour))

[Package ggforce version 0.3.3 Index]