[R] aggregate example : where is the state.region variable?

[John Kane]

--- "Richard M. Heiberger" <rmh at temple.edu> wrote:

> > there is
> > no factor in the dataset but why there is not one
> and
> > why a call to another dataset is totally opaque.  
> 
> The reason is purely historical.  The state dataset
> is about
> 10 years older than the data.frame concept.  At the
> time the
> state.* variables were constructed it was not
> possible to put
> numeric data and factor data into the same
> rectangular structure.

I see. So originally the example would have been more
obvious.  Thanks