N-dimensional identity "matrix" Given a positive integer n, output the N-dimensional identity "matrix", which is the N^N array with 1 where all the components of the indices are equal and 0 otherwise. N^N means N-by-N-by-N-by-...

1 -&gt; [1]

2 -&gt; [[1,0],[0,1]]

3 -&gt; [[[1,0,0],[0,0,0],[0,0,0]],[[0,0,0],[0,1,0],[0,0,0]],[[0,0,0],[0,0,0],[0,0,1]]]

4 -&gt; [[[[1,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0]],[[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0]],[[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0]],[[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0]]],[[[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0]],[[0,0,0,0],[0,1,0,0],[0,0,0,0],[0,0,0,0]],[[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0]],[[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0]]],[[[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0]],[[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0]],[[0,0,0,0],[0,0,0,0],[0,0,1,0],[0,0,0,0]],[[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0]]],[[[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0]],[[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0]],[[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0]],[[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,1]]]]


For example, if a is the 4-dimensional identity "matrix", then the only entries with 1 would be a[0][0][0][0], a[1][1][1][1], a[2][2][2][2], and a[3][3][3][3].

This is code-golf. Shortest answer in bytes wins. Standard loopholes apply.
Octave, 29 bytes

@(n)accumarray((x=1:n)'+!x,1)

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