[Numpy-discussion] possible bug with numpy.object_

Stefan van der Walt stefan at sun.ac.za
Wed Aug 30 07:04:16 CDT 2006


On Tue, Aug 29, 2006 at 10:49:58AM -0600, Travis Oliphant wrote:
> Matt Knox wrote:
> > is the following behaviour expected? or is this a bug with 
> > numpy.object_  ?  I'm using numpy 1.0b1
> >  
> > >>> print numpy.array([],numpy.float64).size
> > 0
> >
> > >>> print numpy.array([],numpy.object_).size
> > 1
> >
> > Should the size of an array initialized from an empty list not always 
> > be 1 ? or am I just crazy?
> >  
> Not in this case.  Explictly creating an object array from any object 
> (even the empty-list object) gives you a 0-d array containing that 
> object.   When you explicitly create an object array a different section 
> of code handles it and gives this result.  This is a recent change, and 
> I don't think this use-case was considered as a backward incompatibility 
> (which I believe it is).   Perhaps we should make it so array([],....) 
> always returns an empty array.   I'm not sure.   Comments?

The current behaviour makes sense, but is maybe not consistent:

N.array([],dtype=object).size == 1
N.array([[],[]],dtype=object).size == 2

Regards
Stéfan




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