combining tables

On 19 Jun 2006, at 12:45, Gabor Grothendieck wrote:

Try this:

both <- c(x,y)
as.table(tapply(both, names(both), sum))

thanks for this, Gabor.

The class of the objects I am manipulating in my
package is c("count", "table").

It'd be nice to overload the "+" symbol so that I can add
two count objects like this with a simple "x+y".  To this end, I
defined a Ops.count() function that executed Gabor's summation.

But, this broke all sorts of functionality in the package,
because the ">" relation was not defined in my Ops.count()
function.

In my case, the only operation that I want to redefine is "+".
I want to leave all the others unchanged.

What is Best Practice for redefining just one binary operator?

On 6/19/06, Robin Hankin <r.hankin at noc.soton.ac.uk> wrote:

Hi

Suppose I have two tables of counts of different animals and I
wish to pool them so the total of the sum is the sum of the total.

Toy example follows (the real ones are ~10^3 species and ~10^6
individuals).
x and y are zoos that have merged and I need a combined inventory
including animals that are temporarily absent.

 > (x <- as.table(c(cats=3,squid=7,pigs=2,dogs=1,slugs=0)))

cats squid  pigs  dogs slugs
    3     7     2     1     0

 > (y <- as.table(c(cats=4,dogs=5,slugs=3,crabs=0)))

cats  dogs slugs crabs
    4     5     3     0

 > (desired.output <- as.table(c

(cats=7,squid=7,pigs=2,dogs=6,slugs=3,crabs=0)))
cats squid  pigs  dogs slugs crabs
    7     7     2     6     3     0

 >

Note that we have 7 cats altogether, and the crabs correctly show
as zero counts.


How to do this nicely in R?