[R] Assigning entries to categories

[David Winsemius]

On Jul 5, 2010, at 8:54 AM, LogLord wrote:

>
> OK, thanks for the help!
>
> Here a more complex example:
>
> a=c("x","y","z")
> b=c(8,14,19)
> c=c(200010,535388,19929)
> data=data.frame(a,b,c)
>
> d=c("cat1","cat2","cat3","cat4","cat5","cat6")
> b1=c(14,5,8,20,19,1)
> c_start=c(500000,500000,200000,200000,18000,600000)
> c_stop=c(550000,550000,201000,201000,20000,700000)
> category=data.frame(d,b1,c_start,c_stop)
>
>
> Again I want to create a new variable, which automatically assigns the
> category to the data based on matching b = b1 and c  >= c_start and
> <=c_stop.
>


Probably not the most elegant solution. For each data row, see which  
one or more rows of category satisfies. Not tested for possibility of  
non-hit:

 > for (i in 1:nrow(data)) print( category[
                       which(apply(category[, -1], 1,
                                    function(x) {data$b[i]==x[1] & data 
$c[i] > x[2] & x[3] > data$c[i]})),
                                             1] )
[1] cat3
Levels: cat1 cat2 cat3 cat4 cat5 cat6
[1] cat1
Levels: cat1 cat2 cat3 cat4 cat5 cat6
[1] cat5
Levels: cat1 cat2 cat3 cat4 cat5 cat6

A couple of points. Bad practice to name variables or objects with the  
name "c". Also bad practice to name objects "data". Both at common R  
function names.

> I hope this explains my problem more explicit.
>
> Thanks!
> -- 
> View this message in context: http://r.789695.n4.nabble.com/Assigning-entries-to-categories-tp2272697p2278334.html
> Sent from the R help mailing list archive at Nabble.com.
>
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David Winsemius, MD
West Hartford, CT