This geom is a cousin of
ggplot2::geom_polygon() with the added
possibility of expanding or contracting the polygon by an absolute amount
(e.g. 1 cm). Furthermore, it is possible to round the corners of the polygon,
again by an absolute amount. The resulting geom reacts to resizing of the
plot, so the expansion/contraction and corner radius will not get distorted.
If no expansion/contraction or corner radius is specified, the geom falls
geom_polygon so there is no performance penality in using this
geom_shape( mapping = NULL, data = NULL, stat = "identity", position = "identity", expand = 0, radius = 0, ..., 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.
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.
Some settings can result in the dissappearance of polygons, specifically when contracting or rounding corners with a relatively large amount. Also note that x and y scale limits does not take expansion into account and the resulting polygon might thus not fit into the plot.
geom_shape understand the following aesthetics (required aesthetics are in bold):
shape <- data.frame( x = c(0.5, 1, 0.75, 0.25, 0), y = c(0, 0.5, 1, 0.75, 0.25) ) # Expand and round ggplot(shape, aes(x = x, y = y)) + geom_shape(expand = unit(1, 'cm'), radius = unit(0.5, 'cm')) + geom_polygon(fill = 'red') # Contract ggplot(shape, aes(x = x, y = y)) + geom_polygon(fill = 'red') + geom_shape(expand = unit(-1, 'cm')) # Only round corners ggplot(shape, aes(x = x, y = y)) + geom_polygon(fill = 'red') + geom_shape(radius = unit(1, 'cm'))