Function interp_split 

fn interp_split(
    positional: &[RValue],
    _named: &[(String, RValue)],
    _context: &BuiltinContext<'_>,
) -> Result<RValue, RError>

Split a vector or data frame into groups defined by a factor.

@param x vector or data frame to split @param f factor or vector defining the groups (same length as x, or nrow(x) for data frames) @param drop if TRUE, drop unused factor levels (currently ignored) @return named list of subsets