geom_segment {ggplot2} | R Documentation

## Line segments and curves.

### Description

`geom_segment` draws a straight line between points (x1, y1) and (x2, y2). `geom_curve` draws a curved line.

### Usage

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

    geom_curve(mapping = NULL, data = NULL, stat = "identity",
      position = "identity", ..., curvature = 0.5, angle = 90, 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.

`stat` | The statistical transformation to use on the data for this layer, as a string.
`position` | Position adjustment, either as a string, or the result of a call to a position adjustment function.
`...` | other arguments passed on to `layer`. These are often aesthetics, used to set an aesthetic to a fixed value, like `color = "red"` or `size = 3`. They may also be parameters to the paired geom/stat.
`arrow` | specification for arrow heads, as created by arrow()
`lineend` | Line end style (round, butt, square)
`na.rm` | If `FALSE` (the default), removes missing values with a warning. If `TRUE` silently removes missing values.
`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.
`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`.
`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.

### Aesthetics

`geom_segment` understands the following aesthetics (required aesthetics are in bold):

- `x`

- `xend`

- `y`

- `yend`

- `alpha`

- `colour`

- `linetype`

- `size`

### See Also

`geom_path` and `geom_line` for multi- segment lines and paths.

`geom_spoke` for a segment parameterised by a location (x, y), and an angle and radius.

### Examples

    b <- ggplot(mtcars, aes(wt, mpg)) +
      geom_point()

    df <- data.frame(x1 = 2.62, x2 = 3.57, y1 = 21.0, y2 = 15.0)
    b +
     geom_curve(aes(x = x1, y = y1, xend = x2, yend = y2, colour = "curve"), data = df) +
     geom_segment(aes(x = x1, y = y1, xend = x2, yend = y2, colour = "segment"), data = df)

    b + geom_curve(aes(x = x1, y = y1, xend = x2, yend = y2), data = df, curvature = -0.2)
    b + geom_curve(aes(x = x1, y = y1, xend = x2, yend = y2), data = df, curvature = 1)
    b + geom_curve(
      aes(x = x1, y = y1, xend = x2, yend = y2),
      data = df,
      arrow = arrow(length = unit(0.03, "npc"))
    )

    ggplot(seals, aes(long, lat)) +
      geom_segment(aes(xend = long + delta_long, yend = lat + delta_lat),
        arrow = arrow(length = unit(0.1,"cm"))) +
      borders("state")

    # You can also use geom_segment to recreate plot(type = "h") :
    counts <- as.data.frame(table(x = rpois(100,5)))
    counts$x <- as.numeric(as.character(counts$x))
    with(counts, plot(x, Freq, type = "h", lwd = 10))

    ggplot(counts, aes(x, Freq)) +
      geom_segment(aes(xend = x, yend = 0), size = 10, lineend = "butt")

[Package ggplot2 version 2.1.0 Index]