Add split violin and split sina

[jdlee]

It would be very useful to be able to create split violin plots such as this:
https://stackoverflow.com/questions/35717353/split-violin-plot-with-ggplot2

Extending this functionality to sina plots would be extremely useful:
https://ggforce.data-imaginist.com/reference/geom_sina.html

[erocoar]

Hi, that's a great suggestion 😄 I've added an optional split aesthetic to the half-violin plot, see example below:

ggplot() +
  geom_half_violin(
    data = ToothGrowth, 
    aes(x = as.factor(dose), y = len, split = supp, fill = supp),
    position = "identity"
  ) + 
  theme_minimal()

Hope it's still of use !