combining tables
On 6/20/06, Robin Hankin <r.hankin at noc.soton.ac.uk> wrote:
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?
This will define + but not the others:
"+.count" <- function(x,y) {
both <- c(x,y)
as.table(tapply(both, names(both), sum))
}