[Numpy-discussion] dtype=object behavior change from 0.9.6 to beta 1

Christopher Barker Chris.Barker at noaa.gov
Thu Aug 31 14:51:07 CDT 2006


Tom Denniston wrote:
> I would think one would want to throw an error when the data has
> inconsistent dimensions.

But it doesn't have inconsistent dimensions - they are perfectly 
consistent with a (2,) array of objects. How is the code to know what 
you intended?

With numeric types, it is unambiguous to march down through the 
sequences until you get a number. As a sequence is an object, there no 
way to unambiguously do this automatically.

Perhaps the way to solve this is for the array constructor to take a 
"shape" or "rank" argument, so you could specify what you intend. But 
that's really just syntactic sugar to avoid for calling numpy.empty() first.

Perhaps a numpy.object_array() constructor would be useful, although as 
I think about it, even specifying a shape or rank would not be unambiguous!

This is a useful discussion. If we ever get a nd-array into the standard 
lib, I suspect that object arrays will get heavy use -- better to clean 
up the semantics now.

Perhaps a Wiki page on building object arrays is called for.

-Chris


-- 
Christopher Barker, Ph.D.
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