[R-sig-Geo] number of triples

[Amen Alyaari]

Dear All,

I have three datasets and would like co know how much N was used in my 
calculations.

I read the data into a multi-dimensional array with dimensions (nx, ny, 
ntsteps, ndatasets), e.g. with a smaller example dataset:

           # nx   ny   nsteps ndatasets
                 dat = runif(20 * 30 * 100 *  3)
             dim(dat) = c(20, 30, 100, 3)
 > str(dat)
         num [1:20, 1:30, 1:100, 1:3] 0.1834 0.8537 0.0672 0.0734 0.8078 ...

we take advantage of the `cor` functions and build this function to 
compute how many N we have:

         cor_withN <- function(...) {
             res <- try(cor.test(...)$parameter+2, silent=TRUE)
             ifelse(class(res)=="try-error", NA, res)}

Now we take advantage of the fact that apply also works on 
multi-dimensional arrays, not only matrices:

We use apply to iterate over all the x,y,z triples.

           result = apply(dat, c(1,2), function(x) cor_withN(x[,1], 
x[,2],x[,3]))
 > str(cor_result)
          logi [1:20, 1:30] NA NA NA NA NA NA ..
so something is wrong by getting NA NA NA NA
if the last line went well! then

          str(cor_result)
  should be

          logi [1:20, 1:30] 100 100 100 100 100 ..(nsteps)

Any idea on why I am getting NA or is there another way to do it?

When I tested it with 2 datsets,it went well!

           cor_result = apply(dat, c(1,2), function(x) cor_withN(x[,1], 
x[,2]))
 > str(cor_result)
          num [1:20, 1:30] 100 100 100 100 100 100 100 100 100 100

so the problem is when I added `x[,3]`!!
Thanks

Amen