[R] map at fips level using multiple variables

[bby2103 at columbia.edu]

Hi David,

Sorry it sounds vague.

Here is my current code, which gives the distribution of family size  
at US county level. You will see on a US map family size distribution  
represented by different colors.

Now if i have another variable income, which has 3 categories(<50k,  
50k-80k,>80k). How do I show 5x3 categories on the map? I guess I  
could always create a third variable to do this. Just wondering maybe  
there is a function to do this readily?

Thank you!
Bonnie Yuan

y=data1$size
x11()
hist(y,nclass=15) # histogram of y
fivenum(y)
# specify the cut-off point of y
y.colorBuckets=as.numeric(cut(y, c(1,2, 3,6)))
# legend showing the cut-off points.
legend.txt=c("0-1","1-2","2-3","3-6",">6")
colorsmatched=y.colorBuckets[match(county.fips$fips,fips[,1])]
x11()
map("county", col = colors[colorsmatched], fill = TRUE, resolution = 0)
map("state", col = "white", fill = FALSE, add = TRUE, lty = 1, lwd = 0.2)
title("Family Size")
legend("bottom", legend.txt, horiz = TRUE, fill = colors, cex=0.7)



Quoting David Winsemius <dwinsemius at comcast.net>:

>
> 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