On Wed, Nov 17, 2010 at 7:48 PM, Nathaniel Smith <[email protected]> wrote: > On Wed, Nov 17, 2010 at 10:32 AM, Sebastian Haase <[email protected]> wrote: >> On Wed, Nov 17, 2010 at 7:26 PM, Robert Kern <[email protected]> wrote: >>> On Wed, Nov 17, 2010 at 12:20, Sebastian Haase <[email protected]> wrote: >>>> Why does numpy not accept float arrays as indices ? >>>> I was very happy and quite surprised once I found out that it worked >>>> at all for Python float scalars, >>>> but would it not just be consequent to also allow float ndarrays then ? >>> >>> It only works for float scalars by accident. Do not rely on it. >> >> Could you be more specific ? As a feature, it for sure can be useful. > > I think Robert Kern has the same intuition as me: that supporting > float indices is pointless. So, can you give any *specific examples* > of things you can do with float indices that would be difficult or > more expensive using integer indices? That's probably the best way to > convince people. > > -- Nathaniel Well, suppose you have 2 vectors of floating point coordinates `x` and `y` and you want to do operations utilizing fancy indexing like image[ [x,y] ] += 1
As I just realized, this specific case seems to be addressed by histogram2d, however, if float indices would work this would of course be much more general: higher dimensionality and not just '+=' operations. Finally, I just started wondering if numexpr could help here: then one could, for example, even do proper rounding (like: image[ [x+.5,y+5] ] += 1) without creating a temporary array. Regards, Sebastian _______________________________________________ NumPy-Discussion mailing list [email protected] http://mail.scipy.org/mailman/listinfo/numpy-discussion
