This is not a base R operator. It is for the `data.table` package. Take a look at the documentation: `library(data.table); help(":=")`.
– lmoJun 10 '16 at 12:14
1
@lmo it actually is a(n undocumented) base R operator - if it wasn't `data.table` (and `ggplot2` and maybe other packages) wouldn't be able to use it as one. It just isn't used for anything in base R.
– eddiJun 10 '16 at 15:27