Re: [Numpy-discussion] Strange inversion in shape with some slices
On Tue, Nov 17, 2009 at 11:24 AM, Jean-Baptiste Rudant boogalo...@yahoo.fr wrote: Hello, I think there's something strange with shape when a slice is given by an array. import numpy as N my_array = N.ones((2, 3, 6)) ind = N.arange(4) #you hope to find (3, 4) print my_array[0, :, ind].shape print my_array[0, :, 0:4].shape print my_array[0][:, ind].shape print my_array[0][:, 0:4].shape (4, 3) (3, 4) (3, 4) (3, 4) Jean-Baptiste Rudant there was a long thread on this with the explanation in March, title is it a bug? Josef ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Strange inversion in shape with some slices
On Tue, Nov 17, 2009 at 5:40 PM, josef.p...@gmail.com wrote: On Tue, Nov 17, 2009 at 11:24 AM, Jean-Baptiste Rudant boogalo...@yahoo.fr wrote: Hello, I think there's something strange with shape when a slice is given by an array. import numpy as N my_array = N.ones((2, 3, 6)) ind = N.arange(4) #you hope to find (3, 4) print my_array[0, :, ind].shape print my_array[0, :, 0:4].shape print my_array[0][:, ind].shape print my_array[0][:, 0:4].shape (4, 3) (3, 4) (3, 4) (3, 4) Jean-Baptiste Rudant there was a long thread on this with the explanation in March, title is it a bug? The thread is here: http://www.mail-archive.com/numpy-discussion@scipy.org/msg16300.html It looks to me like violating the principle of least surprise. My reading of that thread is, that the observed bug is mostly a consequence coming from the way fancy indexing is implemented. How about deprecating this kind of index mixing !? Regards, Sebastian Haase ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Strange inversion in shape with some slices
On Tue, Nov 17, 2009 at 12:33, Sebastian Haase seb.ha...@gmail.com wrote: On Tue, Nov 17, 2009 at 5:40 PM, josef.p...@gmail.com wrote: On Tue, Nov 17, 2009 at 11:24 AM, Jean-Baptiste Rudant boogalo...@yahoo.fr wrote: Hello, I think there's something strange with shape when a slice is given by an array. import numpy as N my_array = N.ones((2, 3, 6)) ind = N.arange(4) #you hope to find (3, 4) print my_array[0, :, ind].shape print my_array[0, :, 0:4].shape print my_array[0][:, ind].shape print my_array[0][:, 0:4].shape (4, 3) (3, 4) (3, 4) (3, 4) Jean-Baptiste Rudant there was a long thread on this with the explanation in March, title is it a bug? The thread is here: http://www.mail-archive.com/numpy-discussion@scipy.org/msg16300.html It looks to me like violating the principle of least surprise. That principle is notoriously unreliable, and I am never convinced by it. My reading of that thread is, that the observed bug is mostly a consequence coming from the way fancy indexing is implemented. How about deprecating this kind of index mixing !? No. When you need it, you need it. -- Robert Kern I have come to believe that the whole world is an enigma, a harmless enigma that is made terrible by our own mad attempt to interpret it as though it had an underlying truth. -- Umberto Eco ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Strange inversion in shape with some slices
On Nov 17, 2009, at 12:33 PM, Sebastian Haase wrote: On Tue, Nov 17, 2009 at 5:40 PM, josef.p...@gmail.com wrote: On Tue, Nov 17, 2009 at 11:24 AM, Jean-Baptiste Rudant boogalo...@yahoo.fr wrote: Hello, I think there's something strange with shape when a slice is given by an array. import numpy as N my_array = N.ones((2, 3, 6)) ind = N.arange(4) #you hope to find (3, 4) print my_array[0, :, ind].shape print my_array[0, :, 0:4].shape print my_array[0][:, ind].shape print my_array[0][:, 0:4].shape (4, 3) (3, 4) (3, 4) (3, 4) Jean-Baptiste Rudant there was a long thread on this with the explanation in March, title is it a bug? The thread is here: http://www.mail-archive.com/numpy-discussion@scipy.org/msg16300.html It looks to me like violating the principle of least surprise. My reading of that thread is, that the observed bug is mostly a consequence coming from the way fancy indexing is implemented. How about deprecating this kind of index mixing !? I don't think this is really a case of the way fancy indexing is implemented. It could have been done in many ways.The problem is one of real ambiguity in the general case and the fact that there wasn't any code written to handle the less ambiguous special-cases like this one. There are real applications of index mixing, so turning it off is not an option. We could perhaps add better handling of circumstances like this, however, with appropriate warnings and transitions. -Travis ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
