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
The data to be displayed in this layer. There are three options:
The statistical transformation to use on the data for this layer, as a string.
Position adjustment, either as a string, or the result of a call to a position adjustment function.
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.
Other arguments passed on to
logical. Should this layer be included in the legends?
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'))