Polygon parameterisation for rastersSource:
geom_polygonraster takes data that describes a raster with pixels of
the same size and reparametrises the data as a polygon. This allows for more
flexible transformations of the data, but comes at an efficiency cost.
geom_polygonraster( mapping = NULL, data = NULL, stat = "identity", position = position_lineartrans(), ..., hjust = 0.5, vjust = 0.5, 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
mappingif there is no plot mapping.
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.
functionwill be called with a single argument, the plot data. The return value must be a
data.frame, and will be used as the layer data. A
functioncan be created from a
~ head(.x, 10)).
The statistical transformation to use on the data for this layer, either as a
Geomsubclass or as a string naming the stat stripped of the
Position adjustment, either as a string naming the adjustment (e.g.
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.
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.
- hjust, vjust
horizontal and vertical justification of the grob. Each justification value should be a number between 0 and 1. Defaults to 0.5 for both, centering each pixel over its data location.
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.
FALSEnever includes, and
TRUEalways includes. It can also be a named logical vector to finely select the aesthetics to display.
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.
For each pixel in a raster, makes a vertex for each of the four
corner points. These coordinates can then by transformed by
coord-functions such as
position-functions such as
position_lineartrans(). Currently substitutes group
aesthetics right before drawing in favour of pixel identifiers.
geom_raster() understands the following aesthetics (required
aesthetics are in bold):
# Combining with coord_polar() ggplot(faithfuld, aes(waiting, eruptions)) + geom_polygonraster(aes(fill = density)) + coord_polar() # Combining with linear transformations df <- data.frame(x = row(volcano)[TRUE], y = col(volcano)[TRUE], z = volcano[TRUE]) ggplot(df, aes(x, y, fill = z)) + geom_polygonraster(position = position_lineartrans(angle = 30, shear = c(1, 0)))