Violin plot.


geom_violin(mapping = NULL, data = NULL, stat = "ydensity", position = "dodge", ..., draw_quantiles = NULL, trim = TRUE, scale = "area", na.rm = FALSE, show.legend = NA, inherit.aes = TRUE)
stat_ydensity(mapping = NULL, data = NULL, geom = "violin", position = "dodge", ..., bw = "nrd0", adjust = 1, kernel = "gaussian", trim = TRUE, scale = "area", na.rm = FALSE, show.legend = NA, inherit.aes = TRUE)


Set of aesthetic mappings created by aes or 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.
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.
Position adjustment, either as a string, or the result of a call to a position adjustment function.
other arguments passed on to layer. These are often aesthetics, used to set an aesthetic to a fixed value, like color = "red" or size = 3. They may also be parameters to the paired geom/stat.
If not(NULL) (default), draw horizontal lines at the given quantiles of the density estimate.
If TRUE (default), trim the tails of the violins to the range of the data. If FALSE, don't trim the tails.
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.
If FALSE (the default), removes missing values with a warning. If TRUE silently removes missing values.
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.
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.
geom, stat
Use to override the default connection between geom_violin and stat_ydensity.
the smoothing bandwidth to be used, see density for details
adjustment of the bandwidth, see density for details
kernel used for density estimation, see density for details


Violin plot.


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

  • x
  • y
  • alpha
  • colour
  • fill
  • linetype
  • size
  • weight

Computed variables

density estimate

density estimate, scaled to maximum of 1

density * number of points - probably useless for violin plots

density scaled for the violin plot, according to area, counts or to a constant maximum width

number of points

width of violin bounding box


Hintze, J. L., Nelson, R. D. (1998) Violin Plots: A Box Plot-Density Trace Synergism. The American Statistician 52, 181-184.


p <- ggplot(mtcars, aes(factor(cyl), mpg)) p + geom_violin()

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")

# Show quartiles p + geom_violin(draw_quantiles = c(0.25, 0.5, 0.75))

# 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") }
Warning message: Removed 53573 rows containing non-finite values (stat_ydensity).

See also

geom_violin for examples, and stat_density for examples with data along the x axis.