R help - Dec 2011 - map at fips level using multiple variables

Hi, I just started playing with county FIPS feature in maps package  
which allows geospatial visualization of variables on US county level.  
Pretty cool.

I did some search but couldn't find answer to this question--how can I  
map more than 2 variables on US map? For example, you can map by the  
breakdown of income or family size. How do you further breakdown based  
on the values of both variables and show them on the county FIPS level?

Thanks in advance!

Bonnie Yuan

On Dec 7, 2011, at 6:12 PM, bby2103 at columbia.edu wrote:
> Hi, I just started playing with county FIPS feature in maps package  
> which allows geospatial visualization of variables on US county  
> level. Pretty cool.
Got code?
>
> I did some search but couldn't find answer to this question--how can  
> I map more than 2 variables on US map?
"2 variables" is a bit on the vague side for programming purposes.
> For example, you can map by the breakdown of income or family size.  
> How do you further breakdown based on the values of both variables  
> and show them on the county FIPS level?
"breakdown" suggests a factor construct. If so, then :

?interaction

But the "show" part of the question remains very vague.

  Can't you be a bit more specific? What DO you want?

-- 
David Winsemius, MD
West Hartford, CT