geom_dotplot. ggplot2 0.9.3.1

Usage

geom_dotplot(mapping = NULL, data = NULL, stat = "bindot", position = "identity", 
  na.rm = FALSE, binwidth = NULL, binaxis = "x", method = "dotdensity", binpositions = "bygroup", 
      stackdir = "up", stackratio = 1, dotsize = 1, stackgroups = FALSE, ...)

Arguments

binaxis: which axis to bin along "x" (default) or "y"
method: "dotdensity" (default) for dot-density binning, or "histodot" for fixed bin widths (like stat_bin)
binwidth: When method is "dotdensity", this specifies maximum bin width. When method is "histodot", this specifies bin width. Defaults to 1/30 of the range of the data
binpositions: When method is "dotdensity", "bygroup" (default) determines positions of the bins for each group separately. "all" determines positions of the bins with all the data taken together; this is used for aligning dot stacks across multiple groups.
stackdir: which direction to stack the dots. "up" (default), "down", "center", "centerwhole" (centered, but with dots aligned)
stackratio: how close to stack the dots. Default is 1, where dots just just touch. Use smaller values for closer, overlapping dots.
dotsize: The diameter of the dots relative to binwidth, default 1.
stackgroups: should dots be stacked across groups? This has the effect that position = "stack" should have, but can't (because this geom has some odd properties).
mapping: The aesthetic mapping, usually constructed with aes or aes_string. Only needs to be set at the layer level if you are overriding the plot defaults.
data: A layer specific dataset - only needed if you want to override the plot defaults.
stat: The statistical transformation to use on the data for this layer.
position: The position adjustment to use for overlappling points on this layer
na.rm: If FALSE (the default), removes missing values with a warning. If TRUE silently removes missing values.
...: other arguments passed on to layer. This can include aesthetics whose values you want to set, not map. See layer for more details.

Description

In a dot plot, the width of a dot corresponds to the bin width (or maximum width, depending on the binning algorithm), and dots are stacked, with each dot representing one observation.

Details

With dot-density binning, the bin positions are determined by the data and binwidth, which is the maximum width of each bin. See Wilkinson (1999) for details on the dot-density binning algorithm.

With histodot binning, the bins have fixed positions and fixed widths, much like a histogram.

When binning along the x axis and stacking along the y axis, the numbers on y axis are not meaningful, due to technical limitations of ggplot2. You can hide the y axis, as in one of the examples, or manually scale it to match the number of dots.

Aesthetics

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

x
y
alpha
colour
fill

References

Wilkinson, L. (1999) Dot plots. The American Statistician, 53(3), 276-281.

Examples

ggplot(mtcars, aes(x = mpg)) + geom_dotplot()

stat_bindot: binwidth defaulted to range/30. Use 'binwidth = x' to adjust this.

ggplot(mtcars, aes(x = mpg)) + geom_dotplot(binwidth = 1.5)



# Use fixed-width bins
ggplot(mtcars, aes(x = mpg)) +
  geom_dotplot(method="histodot", binwidth = 1.5)



# Some other stacking methods
ggplot(mtcars, aes(x = mpg)) +
  geom_dotplot(binwidth = 1.5, stackdir = "center")


ggplot(mtcars, aes(x = mpg)) +
  geom_dotplot(binwidth = 1.5, stackdir = "centerwhole")



# y axis isn't really meaningful, so hide it
ggplot(mtcars, aes(x = mpg)) + geom_dotplot(binwidth = 1.5) +
  scale_y_continuous(name = "", breaks = NA)

Warning message:
breaks = NA is deprecated. Please use breaks = NULL to remove breaks in the scale. (Deprecated; last used in version 0.8.9)


# Overlap dots vertically
ggplot(mtcars, aes(x = mpg)) + geom_dotplot(binwidth = 1.5, stackratio = .7)



# Expand dot diameter
ggplot(mtcars, aes(x  =mpg)) + geom_dotplot(binwidth = 1.5, dotsize = 1.25)




# Examples with stacking along y axis instead of x
ggplot(mtcars, aes(x = 1, y = mpg)) +
  geom_dotplot(binaxis = "y", stackdir = "center")

stat_bindot: binwidth defaulted to range/30. Use 'binwidth = x' to adjust this.


ggplot(mtcars, aes(x = factor(cyl), y = mpg)) +
  geom_dotplot(binaxis = "y", stackdir = "center")

stat_bindot: binwidth defaulted to range/30. Use 'binwidth = x' to adjust this.


ggplot(mtcars, aes(x = factor(cyl), y = mpg)) +
  geom_dotplot(binaxis = "y", stackdir = "centerwhole")

stat_bindot: binwidth defaulted to range/30. Use 'binwidth = x' to adjust this.


ggplot(mtcars, aes(x = factor(vs), fill = factor(cyl), y = mpg)) +
  geom_dotplot(binaxis = "y", stackdir = "center", position = "dodge")

stat_bindot: binwidth defaulted to range/30. Use 'binwidth = x' to adjust this.


# binpositions="all" ensures that the bins are aligned between groups
ggplot(mtcars, aes(x = factor(am), y = mpg)) +
  geom_dotplot(binaxis = "y", stackdir = "center", binpositions="all")

stat_bindot: binwidth defaulted to range/30. Use 'binwidth = x' to adjust this.


# Stacking multiple groups, with different fill
ggplot(mtcars, aes(x = mpg, fill = factor(cyl))) +
  geom_dotplot(stackgroups = TRUE, binwidth = 1, binpositions = "all")



ggplot(mtcars, aes(x = mpg, fill = factor(cyl))) +
  geom_dotplot(stackgroups = TRUE, binwidth = 1, method = "histodot")



ggplot(mtcars, aes(x = 1, y = mpg, fill = factor(cyl))) +
  geom_dotplot(binaxis = "y", stackgroups = TRUE, binwidth = 1, method = "histodot")