Group by multiple columns

[AndreiKingsley]

Is it possible to make a group by several columns (without mappings to other aesthetics)? For example like this:
group = listOf("col1", "col2")

[alshan]

No, collection of column names is not supported as a value of aesthetic. It must be either a name or a collection of values (data).

[alshan]

Just stumbled upon the "interaction" fun in R:
group = interaction(dir, grp)

https://stackoverflow.com/questions/50604055/ggplot2-geom-bar-position-failure