On Thu, Apr 7, 2016 at 12:18 PM Chris Barker <chris.bar...@noaa.gov> wrote:
> On Thu, Apr 7, 2016 at 10:00 AM, Ian Henriksen < > insertinterestingnameh...@gmail.com> wrote: > >> Here's another example that I've seen catch people now and again. >> >> A = np.random.rand(100, 100) >> b = np.random.rand(10) >> A * b.T >> > > typo? that was supposed to be > > b = np.random.rand(100). yes? > Hahaha, thanks, yes, in describing a common typo I demonstrated another one. At least this one doesn't fail silently. > > This is exactly what someone else referred to as the expectations of > someone that comes from MATLAB, and doesn't yet "get" that 1D arrays are 1D > arrays. > > All of this is EXACTLY the motivation for the matric class -- which never > took off, and was never complete (it needed a row and column vector > implementation, if you ask me. But Ithikn the reason it didn't take off is > that it really isn't that useful, but is different enough from regular > arrays to be a greater source of confusion. And it was decided that all > people REALLY wanted was an obviou sway to get matric multiply, which we > now have with @. > Most of the cases I've seen this error have come from people unfamiliar with matlab who, like I said, weren't tracking dimensions quite as carefully as they should have. That said, it's just anecdotal evidence. I wouldn't be at all surprised if this were an issue for matlab users as well. As far as the matrix class goes, we really shouldn't be telling anyone to use that anymore. > > So this discussion brings up that we also need an easy an obvious way to > make a column vector -- > > maybe: > > np.col_vector(arr) > > which would be a synonym for np.reshape(arr, (-1,1)) > > would that make anyone happy? > > NOTE: having transposing a 1D array raise an exception would help remove a > lot of the confusion, but it may be too late for that.... > > > In this case the user pretty clearly meant to be broadcasting along the >> rows of A >> rather than along the columns, but the code fails silently. >> > > hence the exception idea.... > > Yep. An exception may be the best way forward here. My biggest objection is that the current semantics make it easy for people to silently get unintended behavior. > maybe a warning? > > -CHB > > -Ian Henriksen
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