Product of Nonzero Diagonal

easynumpy_linalg

Implement nonzero_product(matrix).

Return the product of the nonzero elements on the main diagonal of a 2D array. If every diagonal element is zero (or there is no diagonal), return None. For example the diagonal of [[1,0,1],[2,0,2],[3,0,3],[4,4,4]] is [1, 0, 3], so the answer is 1 * 3 = 3. No for/while loops.

Constraints

no for/while loops

Your solution

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Hints

Hint 1

np.diag(matrix) extracts the main diagonal; keep the entries that are != 0 with a boolean mask, then np.prod them.