add.scale.bar {ape} | R Documentation

## Add a Scale Bar to a Phylogeny Plot

### Description

This function adds a horizontal bar giving the scale of the branch lengths to a plot of a phylogenetic tree on the current graphical device.

### Usage

    add.scale.bar(x, y, length = NULL, ask = FALSE,
                  lwd = 1, lcol = "black", ...)

### Arguments

`x` | x location of the bar (can be left missing).
`y` | y location of the bar (can be left missing).
`length` | a numeric value giving the length of the scale bar. If none is supplied, a value is calculated from the data.
`ask` | a logical; if `TRUE` the user is asked to click where to draw the bar. The default is `FALSE`.
`lwd` | the width of the bar.
`lcol` | the colour of the bar (use `col` for the colour of the text).
`...` | further arguments to be passed to `text`.

### Details

By default, the bar is placed in a corner of the graph depending on the direction of the tree. Otherwise both `x` and `y` must be specified (if only one is given it is ignored).

The further arguments (`...`) are used to format the text. They may be `font`, `cex`, `col`, and so on (see examples below, and the help page on `text`).

The function `locator` may be used to determine the `x` and `y` arguments.

### Author(s)

Emmanuel Paradis

### See Also

`plot.phylo`, `axisPhylo`, `locator`

### Examples

    tr <- rtree(10)
    layout(matrix(1:2, 2, 1))
    plot(tr)
    add.scale.bar()
    plot(tr)
    add.scale.bar(cex = 0.7, font = 2, col = "red")
    layout(1)

[Package ape version 5.0 Index]