Stratum positions

Given a dataset with alluvial structure, stat_stratum calculates the centroids of the strata at each axis, together with their weights (heights).

stat_stratum(mapping = NULL, data = NULL, geom = "stratum",
  position = "identity", decreasing = NA, reverse = TRUE,
  label.strata = FALSE, show.legend = NA, inherit.aes = TRUE,
  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.
geom	The geometric object to use display the data; override the default.
position	Position adjustment, either as a string, or the result of a call to a position adjustment function.
decreasing	Logical; whether to arrange the strata at each axis in the order of the variable values (NA, the default), in ascending order of total weight (largest on top, FALSE), or in descending order of total weight (largest on bottom, TRUE).
reverse	Logical; if decreasing is NA, whether to arrange the strata at each axis in the reverse order of the variable values, so that they match the order of the values in the legend. Ignored if decreasing is not NA. Defaults to TRUE.
label.strata	Logical; whether to assign the values of the axis variables to the strata. Defaults to FALSE, and requires that no label aesthetic is assigned.
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.
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

stat_stratum requires one of two sets of aesthetics:

• x, stratum, and (optionally) alluvium

• any number of axis[0-9]* (axis1, axis2, etc.)

Use x and stratum for data in lodes format (alluvium is ignored) and axis[0-9]* for data in alluvia format (see is_alluvial). Arguments to parameters inconsistent with the format will be ignored.

Additionally, stat_stratum accepts the following optional aesthetics:

• weight

• label

• group

weight controls the vertical dimensions of the alluvia and are aggregated across equivalent observations. label is used to label the strata and must take a unique value across the observations within each stratum. These and any other aesthetics are aggregated as follows: Numeric aesthetics, including weight, are summed. Character and factor aesthetics, including label, are assigned to strata provided they take unique values across the observations within each stratum (otherwise NA is assigned). group is used internally; arguments are ignored.

See also

layer for additional arguments, geom_stratum for the corresponding geom, and stat_alluvium and geom_alluvium for alluvial flows.

Examples

# only 'stratum' assignment is necessary to generate strata
data(vaccinations)
ggplot(vaccinations,
       aes(weight = freq,
           x = survey, stratum = response,
           fill = response)) +
  stat_stratum(width = .5)

# lode data: positioning with weight labels
ggplot(vaccinations,
       aes(weight = freq,
           x = survey, stratum = response, alluvium = subject,
           label = freq)) +
  stat_stratum(geom = "errorbar") +
  geom_text(stat = "stratum")
# lode data: positioning with stratum labels
ggplot(vaccinations,
       aes(weight = freq,
           x = survey, stratum = response, alluvium = subject,
           label = response)) +
  stat_stratum(geom = "errorbar") +
  geom_text(stat = "stratum")

# alluvium data: positioning with weight labels
ggplot(as.data.frame(Titanic),
       aes(weight = Freq,
           axis1 = Class, axis2 = Sex, axis3 = Age, axis4 = Survived,
           label = Freq)) +
  geom_text(stat = "stratum") +
  stat_stratum(geom = "errorbar") +
  scale_x_continuous(breaks = 1:4,
                     labels = c("Class", "Sex", "Age", "Survived"))
# alluvium data: positioning with stratum labels
ggplot(as.data.frame(Titanic),
       aes(weight = Freq,
           axis1 = Class, axis2 = Sex, axis3 = Age, axis4 = Survived)) +
  geom_text(stat = "stratum", label.strata = TRUE) +
  stat_stratum(geom = "errorbar") +
  scale_x_continuous(breaks = 1:4,
                     labels = c("Class", "Sex", "Age", "Survived"))