[3, 4, 5], [6, 7, 8]]) >>> a[[0,1],[0,1]] array([0, 4]) irb> a = Numo::SFloat.new(3,3).seq => Numo::SFloat#shape=[3,3] [[0, 1, 2], [3, 4, 5], [6, 7, 8]] irb> a[[0,1],[0,1]] => Numo::SFloat(view)#shape=[2,2] [[0, 1], [3, 4]]
irb> a[[0,1],[0,1]].diagonal
=> Numo::SFloat(view)#shape=[2] [0, 4] Future Works Performance Improvement (2) Difference in Advanced Indexing (3) Fix any other places using to_a, each, or map in red chainer.