[NumPy-Tickets] [NumPy] #2006: Why does recarray assignment fail: "cannot call setfield on an object array"?

NumPy Trac numpy-tickets@scipy....
Sun Dec 2 16:46:54 CST 2012


#2006: Why does recarray assignment fail: "cannot call setfield on an object
array"?
----------------------------------------------------------+-----------------
 Reporter:  kevin000                                      |       Owner:  somebody    
     Type:  defect                                        |      Status:  needs_review
 Priority:  normal                                        |   Milestone:  1.7.0       
Component:  numpy.core                                    |     Version:  1.6.2       
 Keywords:  recarray setfield object array runtime error  |  
----------------------------------------------------------+-----------------
Changes (by ChristianMarquardt):

 * cc: christian@… (added)
  * status:  new => needs_review
  * version:  devel => 1.6.2
  * milestone:  Unscheduled => 1.7.0


Comment:

 The same problem occurs in 1.6.2 and 1.7.0b2.

 The (big) change that introduced this behavior is

 https://github.com/numpy/numpy/commit/2635398db3f26529ce2aaea4028a8118844f3c48

 and apparently has introduced the error condition on purpose; there's even
 a test checking that using the setfield() method on an (ordinary) object
 array throws a !RuntimeError.

 As modifying object sub-arrays using the dictionary approach works fine,
 the easiest solution seems to be to replace the setfield() method in the
 __setattr__() method of recarray with ndarray's __setitem__() method; I
 just attached a patch against the 1.7.0b2 distribution of numpy which
 runns successfully through the same tests as the original distribution
 does.

 I know way too little about numpy internals to judge if this patch is
 consistent with the numpy conventions etc.; but keeping this bug in
 recarrays somehow make the whole recarray class superfluous if not fixed
 IMHO.

 Thanks for considering the patch,

    Christian.

-- 
Ticket URL: <http://projects.scipy.org/numpy/ticket/2006#comment:1>
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