A layer is a combination of data, stat and geom with a potential position
adjustment. Usually layers are created using
calls but it can also be created directly using this function.
layer(geom = NULL, stat = NULL, data = NULL, mapping = NULL, position = NULL, params = list(), inherit.aes = TRUE, check.aes = TRUE, check.param = TRUE, subset = NULL, show.legend = NA)
The geometric object to use display the data
The statistical transformation to use on the data for this layer, as a string.
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.
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 mapping.
Position adjustment, either as a string, or the result of a call to a position adjustment function.
Additional parameters to the
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.
TRUE, the default, will check that
supplied parameters and aesthetics are understood by the
FALSE to suppress the checks.
DEPRECATED. An older way of subsetting the dataset used in a layer.
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.
# shortcut for ggplot(mpg, aes(displ, hwy)) + layer(geom = "point", stat = "identity", position = "identity", params = list(na.rm = FALSE) )# use a function as data to plot a subset of global data ggplot(mpg, aes(displ, hwy)) + layer(geom = "point", stat = "identity", position = "identity", data = head, params = list(na.rm = FALSE) )