I'm using np.nonzero to construct the tuple: (array([0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2]), array([1, 3, 5, 7, 2, 3, 6, 7, 4, 5, 6, 7])) Now what I want is the 2-D index array: [1,3,5,7, 2,3,6,7, 4,5,6,7] Any ideas? -- -- Those who don't understand recursion are doomed to repeat it