R help - Aug 2006 - aggregate example : where is the state.region variable?

I was looking ?aggregate and ran the first example

 aggregate(state.x77, list(Region = state.region),
mean)

The variables in state.x77 appear to be :
> state.x77
Population Income Illiteracy Life Exp Murder HS Grad
Frost   Area

Where is the "state.region" variable coming from?

Its not part of state.x77.  Its a completely separate variable.
Try ls("package:datasets") and notice its in the list
or try ?state.region and note that its a variable in datasets.


On 8/21/06, John Kane <jrkrideau at yahoo.ca>
wrote:
> I was looking ?aggregate and ran the first example
>
>  aggregate(state.x77, list(Region = state.region),
> mean)
>
> The variables in state.x77 appear to be :
> > state.x77
> Population Income Illiteracy Life Exp Murder HS Grad
> Frost   Area
>
> Where is the "state.region" variable coming from?
>
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> PLEASE do read the posting guide
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>

On Mon, 21 Aug 2006, John Kane wrote:
> I was looking ?aggregate and ran the first example
> 
>  aggregate(state.x77, list(Region = state.region),
> mean)
> 
> The variables in state.x77 appear to be :
> > state.x77
> Population Income Illiteracy Life Exp Murder HS Grad
> Frost   Area
> 
> Where is the "state.region" variable coming from?
> find("state.region")
[1] "package:datasets"

Try ?state.region for more info.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

> 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.

--- "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