[Numpy-discussion] 1.2 tasks

Darren Dale dsdale24@gmail....
Mon Aug 4 13:16:33 CDT 2008

Hi Jarrod,

I was wondering if someone knowledgeable would please look into the behavior 
of concatenate() with subclasses of ndarray. I posted at scipy-dev some work 
on a subclass that handles units, and when two of these are concatenated, a 
regular ndarray is returned rather than another instance of the subclass. 
This behavior was discussed a while back at 
http://thread.gmane.org/gmane.comp.python.numeric.general/14494 . It 
resurfaced on enthought-dev in Sept-2007, at which point Travis responded (I 
hope he doesnt mind being quoted):

> there should be no array creation functions which do not
> call __array_finalize__ if it is defined, and therefore, the described
> behavior is a bug that should be reported.  The concatentate code should
> also respect the sub-type of the arrays being concatenated (it seems to
> as I look at the code...)
> However, the larger question of priority occurs in mixed concatenation
> cases which are probably being encountered.   In such cases, the
> sub-type with the largest priority will be the resulting type (and if
> it's not your class then your __array_finalize__ will not be called).
> I wonder if this was what was being encountered rather than a
> "limitation of NumPy"

I encountered the problem again over the weekend with the package I am working 
on, which can be checked out from:

"hg clone \ 
http://dale.chess.cornell.edu/~darren/cgi-bin/hgwebdir.cgi/quantities \ 

it installs in the usual way. The concat issue can the be reproduced by doing:

|1> from quantities import NDQuantity
udunits(3): Already initialized from 
file "/usr/lib64/python2.5/site-packages/quantities/quantities-data/udunits.dat"

|2> J=NDQuantity([1.,2.,3.],'J')

|3> J
<3> NDQuantity([ 1.,  2.,  3.]), kg * m^2 / s^2

|4> import numpy

|5> numpy.concatenate([J,J])
<5> array([ 1.,  2.,  3.,  1.,  2.,  3.])

Maybe this is an issue with my code, and not numpy, but since others have 
reported the problem before me, perhaps someone could please have a look 
before releasing 1.2? I dont think array priority is the problem, since I see 
the issue concatenating two of the same array subtypes.


On Monday 04 August 2008 01:45:51 pm Jarrod Millman wrote:
> Here are the remaining tasks that I am aware of that need to be done
> before tagging 1.2.0b1 on the 8th.
> Median
> ======
> The call signature for median needs to change from
>   def median(a, axis=0, out=None, overwrite_input=False):
> to
>   def median(a, axis=None, out=None, overwrite_input=False):
> in both numpy/ma/extras.py and numpy/lib/function_base.py
> Histogram
> ========
> The call signature for histogram needs to change from
>   def histogram(a, bins=10, range=None, normed=False, weights=None,
> new=False): to
>   def histogram(a, bins=10, range=None, normed=False, weights=None,
> new=True): in numpy/lib/function_base.py
> Documentation
> ============
> The documentation project needs to merge in its changes.  Stefan will
> take care of this on the 5th.
> Please let me know ASAP if there is anything I am missing.
> Thanks,

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