add.scale.bar: 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, ...)
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.
...
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.