On Di, 2016-02-23 at 11:45 -0500, Benjamin Root wrote: > but, it isn't really ambiguous, is it? The -1 can only refer to a > single dimension, and if you ignore the zeros in the original and new > shape, the -1 is easily solvable, right?
I think if there is a simple logic (like using 1 for all zeros in both input and output shape for the -1 calculation), maybe we could do it. I would like someone to think about it carefully that it would not also allow some unexpected generalizations. And at least I am getting a BrainOutOfResourcesError right now trying to figure that out :). - Sebastian > Ben Root > > On Tue, Feb 23, 2016 at 11:41 AM, Warren Weckesser < > warren.weckes...@gmail.com> wrote: > > > > > > On Tue, Feb 23, 2016 at 11:32 AM, Benjamin Root < > > ben.v.r...@gmail.com> wrote: > > > Not exactly sure if this should be a bug or not. This came up in > > > a fairly general function of mine to process satellite data. > > > Unexpectedly, one of the satellite files had no scans in it, > > > triggering an exception when I tried to reshape the data from it. > > > > > > >>> import numpy as np > > > >>> a = np.zeros((0, 5*64)) > > > >>> a.shape > > > (0, 320) > > > >>> a.shape = (0, 5, 64) > > > >>> a.shape > > > (0, 5, 64) > > > >>> a.shape = (0, 5*64) > > > >>> a.shape = (0, 5, -1) > > > Traceback (most recent call last): > > > File "<stdin>", line 1, in <module> > > > ValueError: total size of new array must be unchanged > > > > > > So, if I know all of the dimensions, I can reshape just fine. But > > > if I wanted to use the nifty -1 semantic, it completely falls > > > apart. I can see arguments going either way for whether this is a > > > bug or not. > > > > > > > When you try `a.shape = (0, 5, -1)`, the size of the third > > dimension is ambiguous. From the Zen of Python: "In the face of > > ambiguity, refuse the temptation to guess." > > > > Warren > > > > > > > > > > > > Thoughts? > > > > > > Ben Root > > > > > > _______________________________________________ > > > NumPy-Discussion mailing list > > > NumPy-Discussion@scipy.org > > > https://mail.scipy.org/mailman/listinfo/numpy-discussion > > > > > > > _______________________________________________ > > NumPy-Discussion mailing list > > NumPy-Discussion@scipy.org > > https://mail.scipy.org/mailman/listinfo/numpy-discussion > > > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > https://mail.scipy.org/mailman/listinfo/numpy-discussion
signature.asc
Description: This is a digitally signed message part
_______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org https://mail.scipy.org/mailman/listinfo/numpy-discussion
