[R] data.frame with a column containing an array

Rui Barradas
Tue, 09 May 2023 07:32:56 -0000

?s 11:52 de 08/05/2023, Georg Kindermann escreveu:
> Dear list members,
>
> when I create a data.frame containing an array I had expected, that I get a
similar result, when subsetting it, like having a matrix in a data.frame. But
instead I get only the first element and not all values of the remaining
dimensions. Differences are already when creating the data.frame, where I can
use `I` in case of a matrix but for an array I am only able to insert it in a
second step.
>
> DFA <- data.frame(id = 1:2)
> DFA[["ar"]] <- array(1:8, c(2,2,2))
>
> DFA[1,]
> #  id ar
> #1  1  1
>
> DFM <- data.frame(id = 1:2, M = I(matrix(1:4, 2)))
>
> DFM[1,]
> #  id M.1 M.2
> #1  1   1   3
>
> The same when trying to use merge, where only the first value is kept.
>
> merge(DFA, data.frame(id = 1))
> #  id ar
> #1  1  1
>
> merge(DFM, data.frame(id = 1))
> #  id M.1 M.2
> #1  1   1   3
>
> Is there a way to use an array in a data.frame like I can use a matrix in a
data.frame?
>
> I am using R version 4.3.0.
>
> Kind regards,
> Georg
>
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Hello,

Are you looking for something like this?


DFA <- data.frame(id = 1:2)
DFA[["ar"]] <- array(1:8, c(2,2,2))

DFA$ar[1, , ]
#>      [,1] [,2]
#> [1,]    1    5
#> [2,]    3    7


Hope this helps,

Rui Barradas