[Numpy-discussion] array, asarray as contiguous and friends

Travis Oliphant oliphant at ee.byu.edu
Thu Mar 23 12:50:07 CST 2006


Tim Hochberg wrote:

>
>
> I was just looking at the interface for array and asarray to see what 
> other stuff should go in the interface of the hypothetical 
> ascontiguous.  There's 'dtype', which I knew about, and 'fortran', 
> which I didn't, but which makes sense. However, there's also 'ndmin'. 
> First off, it's not described in docstring for asarray, but I was able 
> to find it in the docstring for array without a problem. Second, is it 
> really necessary? It seems to be useful in an awfully narrow set of 
> circumstances, particularly since when you are padding axes not 
> everyone wants to pad to the left.


Padding to the left is "default" behavior for broadcasting and so it 
seems appropriate.  This is how all lower-dimensional arrays are 
interpreted as "higher" dimensional arrays throughout the code.

The ndmin is very handy as atested to by the uses of atleast_1d or 
atleast_2d in numpy library code.   It was added later as an 
optimization step because of the number of library routines that were 
using it.  I've since used it several times to simplify code.  

I think an ascontinguous on the Python level is appropriate since such a 
beast exists on the C-level.   On the other hand, while Tim prefers 
narrow interfaces, the array_from_object interface is traditionally 
pretty broad. 
Thus, in my mind, the array call should get another flag keyword that 
forces a contiguous result.  This translates easily to the C-domain, in 
much the same way as the fortran keyword does.

-Travis





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