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Plot a Hazard Function h(x) = f(x) / S(x)

Source: R/geom_hf.R
geom_hf.Rd

geom_hf() creates a ggplot2 layer that plots a hazard function. Two interfaces are supported:

Usage

geom_hf(
  mapping = NULL,
  data = NULL,
  stat = StatHF,
  position = "identity",
  ...,
  na.rm = FALSE,
  show.legend = NA,
  inherit.aes = FALSE,
  fun = NULL,
  pdf_fun = NULL,
  cdf_fun = NULL,
  xlim = NULL,
  n = 101,
  args = list(),
  pdf_args = NULL,
  cdf_args = NULL,
  color = "black"
)

StatHF

GeomHF

Format

An object of class StatHF (inherits from Stat, ggproto, gg) of length 3.

An object of class GeomHF (inherits from GeomPath, Geom, ggproto, gg) of length 2.

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

Ignored by stat_function(), do not use.

stat

The statistical transformation to use on the data for this layer. When using a geom_*() function to construct a layer, the stat argument can be used to override the default coupling between geoms and stats. The stat argument accepts the following:

  • A Stat ggproto subclass, for example StatCount.

  • A string naming the stat. To give the stat as a string, strip the function name of the stat_ prefix. For example, to use stat_count(), give the stat as "count".

  • For more information and other ways to specify the stat, see the layer stat documentation.

position

A position adjustment to use on the data for this layer. This can be used in various ways, including to prevent overplotting and improving the display. The position argument accepts the following:

  • The result of calling a position function, such as position_jitter(). This method allows for passing extra arguments to the position.

  • A string naming the position adjustment. To give the position as a string, strip the function name of the position_ prefix. For example, to use position_jitter(), give the position as "jitter".

  • For more information and other ways to specify the position, see the layer position documentation.

...

Other parameters passed on to ggplot2::layer().

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. To include legend keys for all levels, even when no data exists, use TRUE. If NA, all levels are shown in legend, but unobserved levels are omitted.

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. annotation_borders().

fun

A hazard function \(h(x)\) (optional). When supplied, pdf_fun and cdf_fun must not be provided.

pdf_fun

A PDF function (e.g. dnorm). Required when fun is not supplied.

cdf_fun

A CDF function (e.g. pnorm). Required when fun is not supplied.

xlim

A numeric vector of length 2 giving the x-range.

n

Number of points at which to evaluate. Defaults to 101.

args

A named list of arguments passed to fun, or shared by both pdf_fun and cdf_fun.

pdf_args

A named list of additional arguments specific to pdf_fun (overrides args). Ignored when using the direct hazard interface.

cdf_args

A named list of additional arguments specific to cdf_fun (overrides args). Ignored when using the direct hazard interface.

color

Line color for the hazard curve.

Value

A ggplot2 layer.

Details

  • PDF + CDF interface: supply pdf_fun and cdf_fun; the hazard is computed internally as \(h(x) = f(x) / (1 - F(x))\).

  • Direct hazard interface: supply fun, a function that returns \(h(x)\) directly (e.g. a closed-form expression).

Exactly one of these two interfaces must be used. By default only the line is drawn (no fill).

Examples

  # PDF + CDF interface
  ggplot() +
    geom_hf(pdf_fun = dnorm, cdf_fun = pnorm, xlim = c(-3, 3))


  ggplot() +
    geom_hf(pdf_fun = dexp, cdf_fun = pexp,
      args = list(rate = 0.5), xlim = c(0, 10))


  # Direct hazard interface (Weibull closed-form hazard)
  h_weibull <- function(x, shape, scale) (shape / scale) * (x / scale)^(shape - 1)
  ggplot() +
    geom_hf(fun = h_weibull, xlim = c(0.01, 5),
      args = list(shape = 0.5, scale = 2))