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Formula interface to stat_density()

Source: R/gf_functions.R
gf_density.Rd

Computes and draws a kernel density estimate, which is a smoothed version of the histogram and is a useful alternative when the data come from an underlying smooth distribution. The only difference between gf_dens() and gf_density() is the default geom used to show the density curve: gf_density() uses an area geom (which can be filled). gf_dens() using a line geom (which cannot be filled).

Usage

gf_density(
  object = NULL,
  gformula = NULL,
  data = NULL,
  ...,
  alpha = 0.5,
  color,
  fill,
  group,
  linetype,
  linewidth,
  kernel = "gaussian",
  n = 512,
  trim = FALSE,
  xlab,
  ylab,
  title,
  subtitle,
  caption,
  geom = "area",
  stat = "density",
  position = "identity",
  show.legend = NA,
  show.help = NULL,
  inherit = TRUE,
  environment = parent.frame()
)

gf_dens(
  object = NULL,
  gformula = NULL,
  data = NULL,
  ...,
  alpha = 0.5,
  color,
  fill = NA,
  group,
  linetype,
  linewidth,
  kernel = "gaussian",
  n = 512,
  trim = FALSE,
  xlab,
  ylab,
  title,
  subtitle,
  caption,
  geom = "line",
  stat = "density",
  position = "identity",
  show.legend = NA,
  show.help = NULL,
  inherit = TRUE,
  environment = parent.frame()
)

gf_dens2(
  object = NULL,
  gformula = NULL,
  data = NULL,
  ...,
  alpha = 0.5,
  color,
  fill = NA,
  group,
  linetype,
  linewidth,
  kernel = "gaussian",
  n = 512,
  trim = FALSE,
  xlab,
  ylab,
  title,
  subtitle,
  caption,
  geom = "density_line",
  stat = "density",
  position = "identity",
  show.legend = NA,
  show.help = NULL,
  inherit = TRUE,
  environment = parent.frame()
)

Arguments

object

When chaining, this holds an object produced in the earlier portions of the chain. Most users can safely ignore this argument. See details and examples.

gformula

A formula with shape ~ x. Faceting can be achieved by including | in the formula.

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)).

...

Additional arguments. Typically these are (a) ggplot2 aesthetics to be set with attribute = value, (b) ggplot2 aesthetics to be mapped with attribute = ~ expression, or (c) attributes of the layer as a whole, which are set with attribute = value.

alpha

Opacity (0 = invisible, 1 = opaque).

color

A color or a formula used for mapping color.

fill

A color for filling, or a formula used for mapping fill.

group

Used for grouping.

linetype

A linetype (numeric or "dashed", "dotted", etc.) or a formula used for mapping linetype.

linewidth

A numerical line width or a formula used for mapping linewidth.

kernel

Kernel. See list of available kernels in density().

n

number of equally spaced points at which the density is to be estimated, should be a power of two, see density() for details

trim

If FALSE, the default, each density is computed on the full range of the data. If TRUE, each density is computed over the range of that group: this typically means the estimated x values will not line-up, and hence you won't be able to stack density values. This parameter only matters if you are displaying multiple densities in one plot or if you are manually adjusting the scale limits.

xlab

Label for x-axis. See also gf_labs().

ylab

Label for y-axis. See also gf_labs().

title, subtitle, caption

Title, sub-title, and caption for the plot. See also gf_labs().

geom, stat

Use to override the default connection between geom_density() and stat_density(). For more information about overriding these connections, see how the stat and geom arguments work.

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.

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.

show.help

If TRUE, display some minimal help.

inherit

A logical indicating whether default attributes are inherited.

environment

An environment in which to look for variables not found in data.

Value

a gg object

Specifying plot attributes

Positional attributes (a.k.a, aesthetics) are specified using the formula in gformula. Setting and mapping of additional attributes can be done through the use of additional arguments. Attributes can be set can be set using arguments of the form attribute = value or mapped using arguments of the form attribute = ~ expression.

In formulas of the form A | B, B will be used to form facets using ggplot2::facet_wrap() or ggplot2::facet_grid(). This provides an alternative to gf_facet_wrap() and gf_facet_grid() that is terser and may feel more familiar to users of lattice.

Evaluation

Evaluation of the ggplot2 code occurs in the environment of gformula. This will typically do the right thing when formulas are created on the fly, but might not be the right thing if formulas created in one environment are used to create plots in another.

See also

gf_ash(), ggplot2::geom_density()

Examples

gf_dens()
#> gf_dens() uses 
#>     * a formula with shape ~x or y ~ .. 
#>     * geom:  line 
#>     * stat:  density 
#>     * key attributes:  alpha = 0.5, color, fill = NA, group, linetype, linewidth,
#>                    kernel = "gaussian", n = 512, trim =
#>                    FALSE
#> 
#> For more information, try ?gf_dens
data(penguins, package = "palmerpenguins")
gf_density(~bill_length_mm, fill = ~species, data = penguins)
#> Warning: Removed 2 rows containing non-finite outside the scale range
#> (`stat_density()`).

gf_dens(~bill_length_mm, color = ~species, data = penguins)
#> Warning: Removed 2 rows containing non-finite outside the scale range
#> (`stat_density()`).

gf_dens2(~bill_length_mm, color = ~species, fill = ~species, data = penguins)
#> Warning: Removed 2 rows containing non-finite outside the scale range
#> (`stat_density()`).

gf_freqpoly(~bill_length_mm, color = ~species, data = penguins, bins = 15)
#> Warning: Removed 2 rows containing non-finite outside the scale range (`stat_bin()`).

# Chaining in the data
data(penguins, package = "palmerpenguins")
penguins |> gf_dens(~bill_length_mm, color = ~species)
#> Warning: Removed 2 rows containing non-finite outside the scale range
#> (`stat_density()`).

# horizontal orientation
penguins |> gf_dens(bill_length_mm ~ ., color = ~species)
#> Warning: Removed 2 rows containing non-finite outside the scale range
#> (`stat_density()`).