ggpointless (version 0.1.0)

geom_lexis: Display events of different cohorts in form of a lexis charts

Description

This geom can be used to plot 45° lifelines for a cohort. Lexis diagrams are named after Wilhelm Lexis and used by demographers for more than a century.

Usage

geom_lexis(
  mapping = NULL,
  data = NULL,
  ...,
  point_show = TRUE,
  point_colour = NULL,
  point_size = deprecated(),
  gap_filler = TRUE,
  lineend = "round",
  linejoin = "round",
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE
)
stat_lexis(
  mapping = NULL,
  data = NULL,
  ...,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = TRUE
)

Arguments

mapping

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.

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)).

...

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.

point_show

logical. Should a point be shown at the end of each segment? TRUE by default

point_colour

color of a point

point_size

deprecated, use size

gap_filler

logical. Should gaps be filled? TRUE by default

lineend

line end style (round, butt, square)

linejoin

line join style (round, mitre, bevel)

na.rm

If FALSE, the default, missing values are removed with a warning. If TRUE, missing values are silently removed.

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().

Aesthetics

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

• x

• xend

• alpha

• color

• fill

• group

• shape

• size

• linetype

• linewidth

• stroke

Details

This geom draws 45° lines from the start to the end of a 'lifetime'. It is a combination of a segment, and a point. Besides y and yend coordinates this geom creates one additional variable called type in the layer data. You might want to map to an aesthetic with ggplot2::after_stat(), see Examples section and vignette("ggpointless") for more details.

Rows in your data with either missing x or xend values will be removed (your segments must start and end somewhere).

Examples

df1 <- data.frame(
  key = c("A", "B", "B", "C", "D", "E"),
  start = c(0, 1, 6, 5, 6, 9),
  end = c(5, 4, 10, 9, 8, 11)
)
p <- ggplot(df1, aes(x = start, xend = end, color = key))
p +
  geom_lexis()
p +
  geom_lexis(gap_filler = FALSE)
p +
  geom_lexis(aes(linetype = after_stat(type)),
    point_show = FALSE
  )

# change point appearance
p + geom_lexis(
  point_colour = "black",
  size = 3,
  shape = 21,
  fill = "white",
  stroke = 1
)

# missing values will be removed
df2 <- data.frame(
  key = c("A", "B", "B", "C", "D"),
  start = c(0, 1, 7, 5, 6),
  end = c(5, 4, 13, 9, NA)
)
ggplot(df2, aes(x = start, xend = end, color = key)) +
  geom_lexis()

# Ideally, `x` values should be increasing, unlike
# in the next example
df3 <- data.frame(x = Sys.Date() - 0:2, xend = Sys.Date() + 1:3)
ggplot(df3, aes(x = x, xend = xend)) +
  geom_lexis()

# If `x` is of class Date, `xend` can't be of class `POSIXt` or
# `POSIXct`. The error is thrown by the `scales::date_trans` function.
if (FALSE) {
ggplot(
  data.frame(x = Sys.Date(), xend = Sys.time()),
  aes(x = x, xend = xend)
) +
  geom_lexis()
}