[Numpy-discussion] Multiarray PEP

Paul Barrett barrett at stsci.edu
Thu Feb 17 05:58:19 EST 2005

Travis Oliphant wrote:
> I am looking for feedback on the PEP.   Of particular interest is the 
> specification of multidimensional indexing that I've outlined.  I think 
> it is mostly the same as numarray (I'd love some feedback to be sure 
> about that), except for the fact that X[K] where K is a a single integer 
> index array can do 1-d indexing similar to MATLAB.  The equivalent 
> numarray indexing is available as X[K,].    Now that I've specified what 
> is to happen, I think it won't be very difficult to code.

Your indexing implementation appears reasonable.

> I would also like some help on resolving the type issue.   Is it 
> important to have hierarchial classes defined (probably in Python) that 
> can be used to check and/or specify type or are functions that check for 
> various properties, fine.   Right now x.type is specified as an 
> attribute but the attribute could be replaced by a method.  What to 
> return is the biggest question.

I don't see the need for hierarchical type classes, though it might ease 
the comparison with Python types.

> I've never had a problem with just the typecode characters although 
> aliases (like Int16 or Short) which might be more meaningful are nice.   
> Are shadow-classes important in this case?  To me they look a little 
> like extra bulk with no gain.  I'd love to be educated as to why it is 
> worth the extra effort to have a bunch of instances lying around.  I 
> don't feel very strongly about this though, so if somebody else does, 
> I'm willing to go for it.

I prefer Int16, UInt16, Float32, Float64, etc. for specifying types. 
They are unambiguous and the scheme is easily extendable.  I also don't 
mind character code aliases for named types as long as they are a 
shorthand for the them and are not used routinely when doing a repr.

  -- Paul

Paul Barrett, PhD      Space Telescope Science Institute
Phone: 410-338-4475    ESS/Science Software Branch
FAX:   410-338-4767    Baltimore, MD 21218

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