[Numpy-discussion] Operation over multiple axes? (Or: Partial flattening?)

Hans Meine meine@informatik.uni-hamburg...
Tue Jul 29 09:24:27 CDT 2008

On Dienstag 29 Juli 2008, Stéfan van der Walt wrote:
> > One way to achieve this is partial flattening, which I did like this:
> >
> >  dat.reshape((numpy.prod(dat.shape[:3]), dat.shape[3])).sum(0)
> >
> > Is there a more elegant way to do this?
> That looks like a good way to do it.  You can clean it up ever so slightly:
> x.reshape([-1, x.shape[-1]]).sum(axis=0)

Thanks, that looks more elegant indeed.  I am not sure if I've read about -1 
in shapes before.  I assume it represents "the automatically determined rest" 
and may only appear once?  Should this be documented in the reshape 

Ciao, /  /                                                    .o.
     /--/                                                     ..o
    /  / ANS                                                  ooo
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