Global Aesthetics Mappings and Side Geometries

library(ggside)
#> Loading required package: ggplot2
#> Registered S3 method overwritten by 'ggside':
#>   method from   
#>   +.gg   ggplot2

The purpose of this vignette is to document a slight change in API expectation with certain geom_*side* when there are global aesthetic mappings for both x and y.

In ggside (<0.1.0), the user was expected to explicitly map all computed aesthetics, especially in the case when x and y are mapped globally for the main panel. The nature of ggside is generally to plot supplemental data, and the user will likely want to inherit the x global mapping if they use a geom_xside* geometry, but map something different to y.

For example take the following example ggplot

p <- ggplot(mpg, aes(displ, hwy, colour = class)) +
  geom_point(size = 2) +
  theme_bw()
p

With the old API, the user could not simply call geom_xsidedensity without specifying aes(y = after_stat(density)).

#geom_xsidedensity_legacy is not exported with new versions of `ggside`
p_error <- p + geom_xsidedensity_legacy()

tryCatch({
  p_error
  },
  error = function(e) e
)
#> Error: geom_xsidedensity requires the following missing aesthetics: y

p + geom_xsidedensity_legacy(aes(y = after_stat(density)))

This decision was made in order to keep all geom_*side* geometries as similar to their ggplot2::geom_* geometry counterparts. However, using ggside becomes a tad bit annoying when you must specify every positional aesthetic, especially when it obvious what the user may want.

In ggside (>=0.1.0), certain geom_*side* geometries will use the default aesthetic mapping of the associated Stat, depending on the orientation parameter.

For example, geom_xsidedensity will ignore the y global mapping and assign y = after_stat(density) to that layer’s aesthetic mappings if no y mapping was specified. The same can be said for geom_ysidedensity, it will ignore the x global mapping and assign x = after_stat(density) if no x mapping was specified.

This should be much less typing.

p + 
  geom_xsidedensity() +
  geom_ysidedensity()

Of course, if you would like to use a different computed variables, you will need to specify it like normal.

p + 
  geom_xsidedensity(aes(y = after_stat(count))) +
  geom_ysidedensity(aes(x = after_stat(scaled)))

You can even use geom_xsidedensity(orientation = "y") to force it to inherit the y global mapping and map x = after_stat(density). I don’t expect many users will do this, but the option is available nonetheless.

#
p + 
  geom_xsidedensity(orientation = "y") #just use geom_ysidedensity()  ¯\_(ツ)_/¯

Side Geometries With Functionality

The following geom_*side* geometries have been updated such that the default expected behavior is easier to use.

This can only be applied to geometries that have a stat other than "identity" with a default_aes. If the geometries have an orientation parameter, this can control which aesthetic is inherited. geom_*sideboxplot and geom_*sideviolin are not included in this update because the orientation largely depends the aesthetic mapping of the layer, and these two geometries could go either way depending on position scales of x and y.

All other geom_*side* geometries will need their mappings to be explicitly assigned or they will try to inherit from the global mapping (so long as inherit.aes = TRUE).