["python","arrays","numpy","indexing"]
How do I access the ith column of a NumPy multidimensional array?

Given: test = np.array([[1, 2], [3, 4], [5, 6]]) test[i] gives the ith row (e.g. [1, 2]). How do I access the ith column? (e.g. [1, 3, 5]). Also, would this be an expensive operation?
With: test = np.array([[1, 2], [3, 4], [5, 6]]) To access column 0: >>> test[:, 0] array([1, 3, 5]) To access row 0: >>> test[0, :] array([1, 2]) This is covered in Section 1.4 (Indexing) of the NumPy reference. This is quick, at least in my experience. It's certainly much quicker than accessing each element in a loop.