split.formula {DescTools}  R Documentation 
Implementation of a simple formula interface for the split
function.
## S3 method for class 'formula'
split(x, f, drop = FALSE, data = NULL, ...)
x 
a formula of the form 
f 
a 'factor' in the sense that 
drop 
logical indicating if levels that do not occur should be dropped (if 
data 
the data frame from which the formula should be evaluated. 
... 
other arguments to be passed to

Andri Signorell <andri@signorell.net>
split(extra ~ group, data = sleep)