[Numpy-discussion] missing array type

Alan G Isaac aisaac at american.edu
Mon Feb 27 15:43:02 CST 2006


On Mon, 27 Feb 2006, Sasha apparently wrote: 
> If you agree that zero-stride array would provide the 
> functionality that you need, it may tip the ballance 
> towards accepting that patch. 

I am out of my technical depth here.  Based on your 
examples, zero-stride arrays seem both logical and 
desirable.  They do seem just right for a simpler (and 
substantially generalized) nd_grid.  But I think they only 
partially address problems two other that have come up.

1. repmat
   http://www.mathworks.com/access/helpdesk/help/techdoc/ref/repmat.html#998661

Perhaps you will say that the best representation of 
a repmat will use 4 dimensions, two with zero strides?
I wonder if a more general cycling is needed for a natural 
repeated matrix.

2. Kronecker product:
   http://www.mathworks.com/access/helpdesk/help/techdoc/ref/kron.html#998881
   This seems a different issue altogether.  I suspect the 
   right way to produce kron(x,y) is usually as a class 
   whose data is x and y, with the Kronecker product never 
   actually stored in memory.  I do not see zero-stride 
   arrays as helping here.

Cheers,
Alan Isaac






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