[R] subsetting 3D array

arun smartpink111 at yahoo.com
Fri Jan 10 07:07:36 CET 2014

```I figured it out:
dim(results[apply(results,1,sum)&TRUE,,])
#[1] 9 3 4
A.K.

On , arun <smartpink111 at yahoo.com> wrote:

dim(results[,,apply(results,3,sum)&TRUE])
#[1] 10  3  4
dim(results[,,abs(apply(results,3,sum))>eps])
#[1] 10  3  4

dim(results2)
#[1] 9 3 4
A.K.

On Friday, January 10, 2014 12:56 AM, Bert Gunter <gunter.berton at gene.com> wrote:
Just use apply() and indexing instead!

results[,,apply(results,3,sum)&TRUE]
## will do it.

However, note that numerical error may make a hash of this. So safer
would be something like:

eps <- 1e-15 ## i.e. something small
results[,,abs(apply(results,3,sum))>eps]

Cheers,
Bert

Bert Gunter
Genentech Nonclinical Biostatistics
(650) 467-7374

"Data is not information. Information is not knowledge. And knowledge
is certainly not wisdom."
H. Gilbert Welch

On Thu, Jan 9, 2014 at 7:23 PM, arun <smartpink111 at yahoo.com> wrote:
> Hi Alex,
> Try:
> set.seed(345)
> results<- array(sample(-5:5,120,replace=TRUE),dim=c(10,3,4))
> indx <- !!apply(results,1,sum)
> library(plyr)
> results2 <- laply(lapply(seq(dim(results)[1]),function(i) results[i,,])[indx],identity)
> attr(results2,"dimnames") <- NULL
>  dim(results2)
> #[1] 9 3 4
>
> A.K.
>
>
>
> I have a 3D array with 13,000 11x8 matrices.
>
> dim(results
> [1] 13000    11     8
>
> Some matrices in the array add up to 0. For example
>
> sum(results[1,,])==0
> [1] TRUE
>
> I would like to remove these. How can I do this?
>
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