Strata at axes

geom_stratum receives a dataset of the horizontal (x) and vertical (y, ymin, ymax) positions of the strata of an alluvial diagram. It plots rectangles for these strata of a provided width.

geom_stratum(mapping = NULL, data = NULL, stat = "stratum",
  position = "identity", show.legend = NA, inherit.aes = TRUE,
  width = 1/3, axis_width = NULL, na.rm = FALSE, ...)

Arguments

mapping	Set of aesthetic mappings created by aes or 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.
data	The data to be displayed in this layer. There are three options: If NULL, the default, the data is inherited from the plot data as specified in the call to ggplot. A 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. A function will 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.
stat	The statistical transformation to use on the data; override the default.
position	Position adjustment, either as a string, or the result of a call to a position adjustment function.
show.legend	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.
inherit.aes	If 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. borders.
width	Numeric; the width of each stratum, as a proportion of the distance between axes. Defaults to 1/3.
axis_width	Deprecated; alias for width.
na.rm	Logical: if FALSE, the default, NA lodes are not included; if TRUE, NA lodes constitute a separate category, plotted in grey (regardless of the color scheme).
...	Additional arguments passed to layer.

Aesthetics

geom_stratum understands the following aesthetics (required aesthetics are in bold):

• x

• y

• ymin

• ymax

• alpha

• colour

• fill

• linetype

• size

• group

group is used internally; arguments are ignored.

See also

layer for additional arguments, and stat_stratum for the corresponding geom.

Examples

# full axis width
ggplot(as.data.frame(Titanic),
       aes(weight = Freq,
           axis1 = Class, axis2 = Sex, axis3 = Age, axis4 = Survived)) +
  geom_stratum(width = 1) + geom_text(stat = "stratum", label.strata = TRUE) +
  scale_x_continuous(breaks = 1:4,
                     labels = c("Class", "Sex", "Age", "Survived"))

# use of facets
ggplot(as.data.frame(Titanic),
       aes(weight = Freq,
           axis1 = Class, axis2 = Sex)) +
  geom_flow(aes(fill = Survived)) +
  geom_stratum() + geom_text(stat = "stratum", label.strata = TRUE) +
  scale_x_continuous(breaks = 1:2, labels = c("Class", "Sex")) +
  facet_wrap(~ Age, scales = "free_y")