ggalluvial (version 0.11.3)

stat_stratum: Stratum positions

Description

Given a dataset with alluvial structure, stat_stratum calculates the centroids (x and y) and heights (ymin and ymax) of the strata at each axis.

Usage

stat_stratum(
  mapping = NULL,
  data = NULL,
  geom = "stratum",
  position = "identity",
  decreasing = ggalluvial_opt("decreasing"),
  reverse = ggalluvial_opt("reverse"),
  absolute = ggalluvial_opt("absolute"),
  discern = FALSE,
  negate.strata = NULL,
  infer.label = FALSE,
  label.strata = NULL,
  min.y = NULL,
  max.y = NULL,
  min.height = NULL,
  max.height = NULL,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE,
  ...
)

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. A function can be created from a formula (e.g. ~ head(.x, 10)).

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 totals (largest on top, FALSE), or in descending order of totals (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.

absolute

Logical; if some cases or strata are negative, whether to arrange them (respecting decreasing and reverse) using negative or absolute values of y.

discern

Passed to to_lodes_form() if data is in alluvia format.

negate.strata

A vector of values of the stratum aesthetic to be treated as negative (will ignore missing values with a warning).

infer.label

Logical; whether to assign the stratum or alluvium variable to the label aesthetic. Defaults to FALSE, and requires that no label aesthetic is assigned. This parameter is intended only for uses in which the data are in alluva form and are therefore converted to lode form before the statistical transformation.

label.strata

Deprecated; alias for infer.label.

min.y, max.y

Numeric; bounds on the heights of the strata to be rendered. Use these bounds to exclude strata outside a certain range, for example when labeling strata using ggplot2::geom_text().

min.height, max.height

Deprecated aliases for min.y and max.y.

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).

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. It can also be a named logical vector to finely select the aesthetics to display.

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().

...

Additional arguments passed to ggplot2::layer().

Aesthetics

stat_alluvium, stat_flow, and stat_stratum require one of two sets of aesthetics:

• x and at least one of alluvium and stratum

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

Use x, alluvium, and/or stratum for data in lodes format and axis[0-9]* for data in alluvia format (see alluvial-data). Arguments to parameters inconsistent with the format will be ignored. Additionally, each stat_*() accepts the following optional aesthetics:

• y

• group

• label

y controls the heights of the alluvia and may be aggregated across equivalent observations. group is used internally; arguments are ignored. label is used to label the strata or lodes and must take a unique value across the observations within each stratum or lode. Often the same variable will be passed to label as to the corresponding alluvial aesthetic (stratum or alluvium).

These and any other aesthetics are aggregated as follows: Numeric aesthetics, including y, are summed. Character and factor aesthetics, including label, are assigned to strata or lodes provided they take unique values across the observations within each (and are otherwise assigned NA).

Package options

stat_stratum, stat_alluvium, and stat_flow order strata and lodes according to the values of several parameters, which must be held fixed across every layer in an alluvial plot. These package-specific options set global values for these parameters that will be defaulted to when not manually set:

• ggalluvial.decreasing (each stat_*): defaults to NA.

• ggalluvial.reverse (each stat_*): defaults to TRUE.

• ggalluvial.absolute (each stat_*): defaults to TRUE.

• ggalluvial.cement.alluvia (stat_alluvium): defaults to FALSE.

• ggalluvial.lode.guidance (stat_alluvium): defaults to "zigzag".

• ggalluvial.lode.ordering (stat_alluvium): defaults to NULL.

• ggalluvial.aes.bind (stat_alluvium and stat_flow): defaults to "none".

See base::options() for how to use options.

Defunct parameters

The previously defunct parameters weight and aggregate.wts have been discontinued. Use y and cement.alluvia instead.

See Also

ggplot2::layer() for additional arguments and geom_stratum() for the corresponding geom.

Other alluvial stat layers: stat_alluvium(), stat_flow()

Examples

# NOT RUN {
# only `stratum` assignment is necessary to generate strata
data(vaccinations)
ggplot(vaccinations,
       aes(y = freq,
           x = survey, stratum = response,
           fill = response)) +
  stat_stratum(width = .5)

# lode data, positioning with y labels
ggplot(vaccinations,
       aes(y = freq,
           x = survey, stratum = response, alluvium = subject,
           label = freq)) +
  stat_stratum(geom = "errorbar") +
  geom_text(stat = "stratum")
# alluvium data, positioning with stratum labels
ggplot(as.data.frame(Titanic),
       aes(y = Freq,
           axis1 = Class, axis2 = Sex, axis3 = Age, axis4 = Survived)) +
  geom_text(stat = "stratum", infer.label = TRUE) +
  stat_stratum(geom = "errorbar") +
  scale_x_discrete(limits = c("Class", "Sex", "Age", "Survived"))

# omit labels for strata outside a y range
ggplot(vaccinations,
       aes(y = freq,
           x = survey, stratum = response,
           fill = response, label = response)) +
  stat_stratum(width = .5) +
  geom_text(stat = "stratum", min.y = 100)

# date-valued axis variables
survey_dates <- data.frame(
  survey = levels(vaccinations$survey),
  start = as.Date(c("2010-09-22", "2015-06-04", "2016-09-27")),
  end = as.Date(c("2010-10-25", "2015-10-05", "2016-10-25"))
)
ggplot(merge(vaccinations, survey_dates, by = "survey"),
       aes(x = end, y = freq, stratum = response, alluvium = subject,
           fill = response)) +
  stat_alluvium(geom = "flow", lode.guidance = "forward",
                width = 30, knot.pos = 0) +
  stat_stratum(width = 30) +
  labs(x = "Survey date", y = "Number of respondents")

# use negative y values to encode rejection versus acceptance
admissions <- as.data.frame(UCBAdmissions)
admissions <- transform(admissions, Count = Freq * (-1) ^ (Admit == "Rejected"))
ggplot(admissions,
       aes(y = Count, axis1 = Dept, axis2 = Gender)) +
  geom_alluvium(aes(fill = Dept), width = 1/12) +
  geom_stratum(width = 1/12, fill = "black", color = "grey") +
  geom_label(stat = "stratum", infer.label = TRUE, min.y = 200) +
  scale_x_discrete(limits = c("Department", "Gender"), expand = c(.05, .05))
# }