[Numpy-discussion] Z-ordering (Morton ordering) for numpy

[Travis Oliphant]

This is pretty cool.    Something like this would be interesting to play with.  There are some algorithms that are faster with z-order arrays.    The code is simple enough and small enough that I could see putting it in NumPy.   What do others think?

-Travis



On Nov 24, 2012, at 1:03 PM, Gamblin, Todd wrote:

> Hi all,
> 
> In the course of developing a network mapping tool I'm working on, I also developed some python code to do arbitrary-dimensional z-order (morton order) for ndarrays.  The code is here:
> 
> 	https://github.com/tgamblin/rubik/blob/master/rubik/zorder.py
> 
> There is a function to put the elements of an array in Z order, and another one to enumerate an array's elements in Z order.  There is also a ZEncoder class that can generate Z-codes for arbitrary dimensions and bit widths.
> 
> I figure this is something that would be generally useful.  Any interest in having this in numpy?  If so, what should the interface look like and can you point me to a good spot in the code to add it?
> 
> I was thinking it might make sense to have a Z-order iterator for ndarrays, kind of like ndarray.flat.  i.e.:
> 
> 	arr = np.empty([4,4], dtype=int)
> 	arr.flat = range(arr.size)
> 	for elt in arr.zorder:
> 		print elt,
> 	0 4 1 5 8 12 9 13 2 6 3 7 10 14 11 15
> 
> Or an equivalent to ndindex:
> 
> 	arr = np.empty(4,4, dtype=int)
> 	arr.flat = range(arr.size)
> 	for ix in np.zindex(arr.shape):
> 		print ix,
> 	(0, 0) (1, 0) (0, 1) (1, 1) (2, 0) (3, 0) (2, 1) (3, 1) (0, 2) (1, 2) (0, 3) (1, 3) (2, 2) (3, 2) (2, 3) (3, 3)
> 
> Thoughts?
> 
> -Todd
> ______________________________________________________________________
> Todd Gamblin, tgamblin@llnl.gov, http://people.llnl.gov/gamblin2
> CASC @ Lawrence Livermore National Laboratory, Livermore, CA, USA
> 
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