This geom lets you annotate sets of points via ellipses. The enclosing ellipses are estimated using the Khachiyan algorithm which guarantees an optimal solution within the given tolerance level. As this geom is often expanded it is of lesser concern that some points are slightly outside the ellipsis. The Khachiyan algorithm has polynomial complexity and can thus suffer from scaling issues. Still, it is only calculated on the convex hull of the groups, so performance issues should be rare (it can easily handle a hull consisting of 1000 points).
geom_mark_ellipse( mapping = NULL, data = NULL, stat = "identity", position = "identity", expand = unit(5, "mm"), radius = expand, n = 100, tol = 0.01, label.margin = margin(2, 2, 2, 2, "mm"), label.width = NULL, label.minwidth = unit(50, "mm"), label.hjust = 0, label.fontsize = 12, label.family = "", label.lineheight = 1, label.fontface = c("bold", "plain"), label.fill = "white", label.colour = "black", label.buffer = unit(10, "mm"), con.colour = "black", con.size = 0.5, con.type = "elbow", con.linetype = 1, con.border = "one", con.cap = unit(3, "mm"), con.arrow = NULL, ..., na.rm = FALSE, show.legend = NA, inherit.aes = TRUE )
Set of aesthetic mappings created by
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
The data to be displayed in this layer. There are three options:
NULL, the default, the data is inherited from the plot
data as specified in the call to
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.
function will be called with a single argument,
the plot data. The return value must be a
will be used as the layer data. A
function can be created
~ head(.x, 10)).
The statistical transformation to use on the data for this
layer, either as a
Geom subclass or as a string naming the
stat stripped of the
stat_ prefix (e.g.
"count" rather than
Position adjustment, either as a string naming the adjustment
"jitter" to use
position_jitter), or the result of a call to a
position adjustment function. Use the latter if you need to change the
settings of the adjustment.
A numeric or unit vector of length one, specifying the expansion amount. Negative values will result in contraction instead. If the value is given as a numeric it will be understood as a proportion of the plot area width.
expand but specifying the corner radius.
The number of points used to draw each ellipse. Defaults to
The tolerance cutoff. Lower values will result in ellipses closer
to the optimal solution. Defaults to
The margin around the annotation boxes, given by a call
A fixed width for the label. Set to
NULL to let the text
The minimum width to provide for the description. If the size of the label exceeds this, the description is allowed to fill as much as the label.
The horizontal justification for the annotation. If it contains two elements the first will be used for the label and the second for the description.
The size of the text for the annotation. If it contains two elements the first will be used for the label and the second for the description.
The font family used for the annotation. If it contains two elements the first will be used for the label and the second for the description.
The height of a line as a multipler of the fontsize. If it contains two elements the first will be used for the label and the second for the description.
The font face used for the annotation. If it contains two elements the first will be used for the label and the second for the description.
The fill colour for the annotation box.
The text colour for the annotation. If it contains two elements the first will be used for the label and the second for the description.
The size of the region around the mark where labels cannot be placed.
The colour for the line connecting the annotation to the mark.
The width of the connector.
The type of the connector. Either
The linetype of the connector.
The bordertype of the connector. Either
"one" (to draw a
line on the horizontal side closest to the mark),
"all" (to draw a border
on all sides), or
"none" (not going to explain that one).
The distance before the mark that the line should stop at.
An arrow specification for the connection using
grid::arrow() for the end pointing towards the mark.
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.
FALSE, the default, missing values are removed with
a warning. If
TRUE, missing values are silently removed.
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
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.
geom_mark_ellipse understands the following aesthetics (required aesthetics are
x0 (used to anchor the label)
y0 (used to anchor the label)
geom_mark_* allow you to put descriptive textboxes connected to the
mark on the plot, using the
description aesthetics. The
textboxes are automatically placed close to the mark, but without obscuring
any of the datapoints in the layer. The placement is dynamic so if you resize
the plot you'll see that the annotation might move around as areas become big
enough or too small to fit the annotation. If there's not enough space for
the annotation without overlapping data it will not get drawn. In these cases
try resizing the plot, change the size of the annotation, or decrease the
buffer region around the marks.
Often marks are used to draw attention to, or annotate specific features of
the plot and it is thus not desirable to have marks around everything. While
it is possible to simply pre-filter the data used for the mark layer, the
geom_mark_* geoms also comes with a dedicated
filter aesthetic that, if
set, will remove all rows where it evalutates to
FALSE. There are
multiple benefits of using this instead of prefiltering. First, you don't
have to change your data source, making your code more adaptable for
exploration. Second, the data removed by the filter aesthetic is remembered
by the geom, and any annotation will take care not to overlap with the
ggplot(iris, aes(Petal.Length, Petal.Width)) + geom_mark_ellipse(aes(fill = Species, filter = Species != 'versicolor')) + geom_point() # Add annotation ggplot(iris, aes(Petal.Length, Petal.Width)) + geom_mark_ellipse(aes(fill = Species, label = Species)) + geom_point() # Long descriptions are automatically wrapped to fit into the width iris$desc <- c( 'A super Iris - and it knows it', 'Pretty mediocre Iris, but give it a couple of years and it might surprise you', "You'll never guess what this Iris does every Sunday" )[iris$Species] ggplot(iris, aes(Petal.Length, Petal.Width)) + geom_mark_ellipse(aes(fill = Species, label = Species, description = desc, filter = Species == 'setosa')) + geom_point() # Change the buffer size to move labels farther away (or closer) from the # marks ggplot(iris, aes(Petal.Length, Petal.Width)) + geom_mark_ellipse(aes(fill = Species, label = Species), label.buffer = unit(40, 'mm')) + geom_point() # The connector is capped a bit before it reaches the mark, but this can be # controlled ggplot(iris, aes(Petal.Length, Petal.Width)) + geom_mark_ellipse(aes(fill = Species, label = Species), con.cap = 0) + geom_point()