merge counts from table()

Hi everyone,

Is there an easy way to combine the counts from table()?

Let's say that I have:
x<-1:4
y<-2:5

I want to replicate:
table(c(x,y))

using only table(x) and table(y) as input.

The reason is that it's cumbersome to carry all the values around when all I care about are the counts. The actual situation has about a billion counts over ~150 categories.

I know there's got to be a number of ways of doing things (plyr comes to mind), but I can't seem to find how to accomplish it.

Thanks,

Fran?ois Pepin