You can do this with the pretty basic scheme of:
(A) Enumerate all indicies
(B) Count the number of equal parts of each index
(C) Indicate those whose equal-part-count is 2 or more.
Thus:
indA =. $ #: [: i. */@: $ NB. Enumerate
indB =. { @: (i.&.>) @: $
eqInd =. [: >./ #/.~ NB. Count
gdA =: $ $ 1 < eqInd"1@:indA f. NB. Indicate
gdB =: 1 < eqInd&>@:indB f.
gdA i. 3 3
1 0 0
0 1 0
0 0 1
gdB i. 3 3
1 0 0
0 1 0
0 0 1
This will not be efficient for large arguments.
-Dan
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