Dnia piątek, 21 listopada 2014 00:09:51 Nathaniel Smith pisze: > On Thu, Nov 20, 2014 at 5:47 PM, Marek Wojciechowski <mw...@p.lodz.pl> wrote: > > Hi! > > > > I wrote a simple subclass of np.ndarray and now i do call np.sum() on it. > > I > > expected that the result will be a python float (or int) just like when > > summing up regular arrays. Instead i obtain the (scalar) view of my > > subclass. How can i change this behavior? I tried writing __array_wrap__ > > method like this:> > > def __array_wrap__(self, out_arr, context=None): > > selfv = self.view(np.ndarray) > > return np.ndarray.__array_wrap__(selfv, out_arr, context) > > > > but this just returns np.ndarray type and not float. > > There isn't really any reason to call __array_wrap__ here. Just > compute whatever value you want and return it. If you want a float > then return that :-). (Something like > if selfv.ndim == 0: > return selfv[()] > ) > > As a bit of advice, if you can possibly avoid subclassing ndarray, > then you probably should. There are a lot of painful little quirks > that you'll run into.
Thanks for the answer. I thought similar, but the 'context' argument confused me a bit. I do not know what for it is here. Thanks also for the (reasonable) advice. Subclassing was just the fastest way to implement what i wanted to do, because of all these methods being on place. However i do see now, that that was not necessarily the best choice... -- Marek Wojciechowski _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
