Hello,
Yes, although there is an accepted solution, I believe you should post
this solution there. It's a base R solution, what the question asks for.
And thanks, I would have never reminded myself of slice.index.
Rui Barradas
Às 20:45 de 12/02/21, robin hankin escreveu:
Rui
> x <- array(runif(60), dim = c(10, 2, 3))
> array(x[slice.index(x,1) %in% 1:5],c(5,dim(x)[-1]))
(I don't see this on stackoverflow; should I post this there too?) Most
of the magic package is devoted to handling arrays of arbitrary
dimensions and this functionality might be good to include if anyone
would find it useful.
HTH
Robin
<mailto:hankin.ro...@gmail.com>
On Sat, Feb 13, 2021 at 12:26 AM Rui Barradas <ruipbarra...@sapo.pt
<mailto:ruipbarra...@sapo.pt>> wrote:
Hello,
This came up in this StackOverflow post [1].
If x is an array with n dimensions, how to subset by just one dimension?
If n is known, it's simple, add the required number of commas in their
proper places.
But what if the user doesn't know the value of n?
The example below has n = 3, and subsets by the 1st dim. The apply loop
solves the problem as expected but note that the index i has
length(i) > 1.
x <- array(1:60, dim = c(10, 2, 3))
d <- 1L
i <- 1:5
apply(x, MARGIN = -d, '[', i)
x[i, , ]
If length(i) == 1, argument drop = FALSE doesn't work as I expected it
to work, only the other way does:
i <- 1L
apply(x, MARGIN = -d, '[', i, drop = FALSE)
x[i, , drop = FALSE]
What am I missing?
[1]
https://stackoverflow.com/questions/66168564/is-there-a-native-r-syntax-to-extract-rows-of-an-array
Thanks in advance,
Rui Barradas
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