On Tue, 2023-06-20 at 12:07 -0400, Robert Kern wrote: > On Tue, Jun 20, 2023 at 11:38 AM Daniel Salles Civitarese < > sall...@br.ibm.com> wrote: > > > ### Proposed new feature or change: > > > > I work with geospatial data that requires tensors with many > > dimensions. > > One challenge I used to have was when I had to implement a > > `__getitem__` to > > access those tensors using a 1D index. One use case is machine > > learning, > > when one needs to feed models sequentially with sub-tensors of the > > original > > one. A simple example is a matrix of shape 2x2 that has the > > positions `(0, > > 0)`, `(0, 1)`, `(1, 0)`, `(1, 1)`, and I want to access it via > > indices `[0, > > 1, 2, 3]`. So, when I say `__getitem__(2)`, I want the position > > `(1, 0)`. > > > > If the only reason you want to compute the indices is to access the > data > using those flattened indices, we use the `.flat` property instead > and > avoid explicitly computing those indices.
We also do have `np.unravel_indices`, which does exactly the thing requested I believe. - Sebsatian > > ``` > [~] > > 21> x = np.arange(2*3).reshape((2, 3)) > > [~] > > 22> x > array([[0, 1, 2], > [3, 4, 5]]) > > [~] > > 23> x.flat[[0, 1, 2, 3]] > array([0, 1, 2, 3]) > ``` > > _______________________________________________ > NumPy-Discussion mailing list -- numpy-discussion@python.org > To unsubscribe send an email to numpy-discussion-le...@python.org > https://mail.python.org/mailman3/lists/numpy-discussion.python.org/ > Member address: sebast...@sipsolutions.net _______________________________________________ NumPy-Discussion mailing list -- numpy-discussion@python.org To unsubscribe send an email to numpy-discussion-le...@python.org https://mail.python.org/mailman3/lists/numpy-discussion.python.org/ Member address: arch...@mail-archive.com
