[Numpy-discussion] Should 0-d arrays with fields defined return a 0-d array or a scalar

Christopher Hanley chanley@stsci....
Thu Mar 29 15:18:28 CDT 2007

Hi Travis,

We will need a little time to inspect our code to see if this is going 
to be a problem for us.  We can't think of any major problems with this 
change off the top of our heads.


Travis Oliphant wrote:
> Hi all,
> Ticket #474 discusses the problem that getting a field from a 0-d array 
> automatically produces a scalar (which then cannot be set).
> This produces the problem that recarrays code must often special-case 
> the 0-d possibility.
> Thus,
> rarr.x[...] = blah
> doesn't work for 0-d arrays because rarr.x is a scalar.
> It makes some sense to make field selection for 0-d arrays return 0-d 
> arrays as consistent with the changes that were made prior to the 1.0 
> release to allow persistence of 0-d arrays.
> However, changing field selection to return 0-d arrays does change 
> behavior.  A 0-d array is not a scalar (the 0-d array is not hashable 
> for example, and the 0-d string array does not inherit from the Python 
> string).  Thus, just making the change, may not be advised.
> It is easy to account for and fix any errors that might arise.  But, we 
> are in a major release, I need some advice as to whether or not this is 
> a "bug-fix" or a feature enhancement that must wait for 1.1?
> Any stake holders in the current behavior of arrays with records?
> -Travis
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Christopher Hanley
Systems Software Engineer
Space Telescope Science Institute
3700 San Martin Drive
Baltimore MD, 21218
(410) 338-4338

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