[R] how to join two arrays using their column names intersection

[Federico Abascal]

Dear all,

I have a problem that may be someone of you can help. I am a newbie and
do not find how to do it in manuals.

I have two arrays, for example:

ar1 <- array(data=c(1:16),dim=c(4,4))
ar2 <- array(data=c(1:16),dim=c(4,4))
colnames(ar1)<-c("A","B","D","E")
colnames(ar2)<-c("C","A","E","B")

> ar1
     A B  D  E
[1,] 1 5  9 13
[2,] 2 6 10 14
[3,] 3 7 11 15
[4,] 4 8 12 16
> ar2
     C A  E  B
[1,] 1 5  9 13
[2,] 2 6 10 14
[3,] 3 7 11 15
[4,] 4 8 12 16


I would like to join both arrays only for the columns present in both
ar1 and ar2 (the intersection). I would like to obtain this:
     A B  E
[1,] 1 5 13
[2,] 2 6 14
[3,] 3 7 15
[4,] 4 8 16
[5,] 5 13  9
[6,] 6 14 10
[7,] 7 15 11
[8,] 8 16 12

(rows 5-8 correspond to ar2)

I have tried several things but I am unable to accomplish it. Any
experienced user could give me some advice, please?

I have another question: how can I sort the columns of an array
according to its column names (for ar2, change CAEB to ABCE)?

Thanks in advance!
Federico