geom_violin.Rd

% Generated by roxygen2 (4.1.1): do not edit by hand
% Please edit documentation in R/geom-violin.r, R/stat-ydensity.r
\name{geom_violin}
\alias{geom_violin}
\alias{stat_ydensity}
\title{Violin plot.}
\usage{
geom_violin(mapping = NULL, data = NULL, stat = "ydensity",
  position = "dodge", trim = TRUE, scale = "area", show.legend = NA,
  inherit.aes = TRUE, ...)

stat_ydensity(mapping = NULL, data = NULL, geom = "violin",
  position = "dodge", adjust = 1, kernel = "gaussian", trim = TRUE,
  scale = "area", na.rm = FALSE, show.legend = NA, inherit.aes = TRUE,
  ...)
}
\arguments{
\item{mapping}{The aesthetic mapping, usually constructed with
\code{\link{aes}} or \code{\link{aes_string}}. Only needs to be set
at the layer level if you are overriding the plot defaults.}

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

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

\item{trim}{If \code{TRUE} (default), trim the tails of the violins
to the range of the data. If \code{FALSE}, don't trim the tails.}

\item{scale}{if "area" (default), all violins have the same area (before trimming
the tails). If "count", areas are scaled proportionally to the number of
observations. If "width", all violins have the same maximum width.}

\item{show.legend}{logical. Should this layer be included in the legends?
\code{NA}, the default, includes if any aesthetics are mapped.
\code{FALSE} never includes, and \code{TRUE} always includes.}

\item{inherit.aes}{If \code{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. \code{\link{borders}}.}

\item{...}{other arguments passed on to \code{\link{layer}}. There are
  three types of arguments you can use here:

  \itemize{
  \item Aesthetics: to set an aesthetic to a fixed value, like
     \code{color = "red"} or \code{size = 3}.
  \item Other arguments to the layer, for example you override the
    default \code{stat} associated with the layer.
  \item Other arguments passed on to the stat.
  }}

\item{geom,stat}{Use to override the default connection between
\code{geom_violin} and \code{stat_ydensity}.}

\item{adjust}{see \code{\link{density}} for details}

\item{kernel}{kernel used for density estimation, see
\code{\link{density}} for details}

\item{na.rm}{If \code{FALSE} (the default), removes missing values with
a warning. If \code{TRUE} silently removes missing values.}
}
\description{
Violin plot.
}
\section{Aesthetics}{

\Sexpr[results=rd,stage=build]{ggplot2:::rd_aesthetics("geom", "violin")}
}

\section{Computed variables}{

\describe{
  \item{density}{density estimate}
  \item{scaled}{density estimate, scaled to maximum of 1}
  \item{count}{density * number of points - probably useless for violin plots}
  \item{violinwidth}{density scaled for the violin plot, according to area, counts
                     or to a constant maximum width}
  \item{n}{number of points}
  \item{width}{width of violin bounding box}
}
}
\examples{
p <- ggplot(mtcars, aes(factor(cyl), mpg))
p + geom_violin()

\donttest{
p + geom_violin() + geom_jitter(height = 0)
p + geom_violin() + coord_flip()

# Scale maximum width proportional to sample size:
p + geom_violin(scale = "count")

# Scale maximum width to 1 for all violins:
p + geom_violin(scale = "width")

# Default is to trim violins to the range of the data. To disable:
p + geom_violin(trim = FALSE)

# Use a smaller bandwidth for closer density fit (default is 1).
p + geom_violin(adjust = .5)

# Add aesthetic mappings
# Note that violins are automatically dodged when any aesthetic is
# a factor
p + geom_violin(aes(fill = cyl))
p + geom_violin(aes(fill = factor(cyl)))
p + geom_violin(aes(fill = factor(vs)))
p + geom_violin(aes(fill = factor(am)))

# Set aesthetics to fixed value
p + geom_violin(fill = "grey80", colour = "#3366FF")

# Scales vs. coordinate transforms -------
if (require("ggplot2movies")) {
# Scale transformations occur before the density statistics are computed.
# Coordinate transformations occur afterwards.  Observe the effect on the
# number of outliers.
m <- ggplot(movies, aes(y = votes, x = rating, group = cut_width(rating, 0.5)))
m + geom_violin()
m + geom_violin() + scale_y_log10()
m + geom_violin() + coord_trans(y = "log10")
m + geom_violin() + scale_y_log10() + coord_trans(y = "log10")

# Violin plots with continuous x:
# Use the group aesthetic to group observations in violins
ggplot(movies, aes(year, budget)) + geom_violin()
ggplot(movies, aes(year, budget)) +
  geom_violin(aes(group = cut_width(year, 10)), scale = "width")
}
}
}
\references{
Hintze, J. L., Nelson, R. D. (1998) Violin Plots: A Box
Plot-Density Trace Synergism. The American Statistician 52, 181-184.
}
\seealso{
\code{\link{geom_violin}} for examples, and \code{\link{stat_density}}
  for examples with data along the x axis.
}