Display a smooth density estimate.

Description

A kernel density estimate, useful for display the distribution of variables with underlying smoothness.

Usage

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geom_bkde(mapping = NULL, data = NULL, stat = "bkde",
  position = "identity", bandwidth = NULL, range.x = NULL,
  na.rm = FALSE, show.legend = NA, inherit.aes = TRUE, ...)

stat_bkde(mapping = NULL, data = NULL, geom = "area",
  position = "stack", kernel = "normal", canonical = FALSE,
  bandwidth = NULL, gridsize = 410, range.x = NULL, truncate = TRUE,
  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), is combined with the default mapping at the top level of the plot. You only need to supply mapping if there isn't a mapping defined for the plot.

data

A data frame. If specified, overrides the default data frame defined at the top level of the plot.

position

Position adjustment, either as a string, or the result of a call to a position adjustment function.

bandwidth

the kernel bandwidth smoothing parameter. see bkde for details. If NULL, it will be computed for you but will most likely not yield optimal results.

range.x

vector containing the minimum and maximum values of x at which to compute the estimate. see bkde for details

na.rm

If FALSE (the default), removes missing values with a warning. If TRUE silently removes missing values.

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.

...

other arguments passed on to layer. There are three types of arguments you can use here:

  • Aesthetics: to set an aesthetic to a fixed value, like color = "red" or size = 3.

  • Other arguments to the layer, for example you override the default stat associated with the layer.

  • Other arguments passed on to the stat.

geom, stat

Use to override the default connection between geom_bkde and stat_bkde.

kernel

character string which determines the smoothing kernel. see bkde for details

canonical

logical flag: if TRUE, canonically scaled kernels are used. see bkde for details

gridsize

the number of equally spaced points at which to estimate the density. see bkde for details.

truncate

logical flag: if TRUE, data with x values outside the range specified by range.x are ignored. see bkde for details

Details

A sample of the output from geom_bkde():

Figure: geom\_bkde\_01.png

Aesthetics

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

  • x

  • y

  • alpha

  • color

  • fill

  • linetype

  • size

Computed variables

density

density estimate

count

density * number of points - useful for stacked density plots

scaled

density estimate, scaled to maximum of 1

See Also

See geom_histogram, geom_freqpoly for other methods of displaying continuous distribution. See geom_violin for a compact density display.

Examples

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data(geyser, package="MASS")

ggplot(geyser, aes(x=duration)) +
  stat_bkde(alpha=1/2)

ggplot(geyser, aes(x=duration)) +
  geom_bkde(alpha=1/2)

ggplot(geyser, aes(x=duration)) +
 stat_bkde(bandwidth=0.25)

ggplot(geyser, aes(x=duration)) +
  geom_bkde(bandwidth=0.25)