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

[NumPy Trac]

#2006: Why does recarray assignment fail: "cannot call setfield on an object
array"?
----------------------------------------------------------+-----------------
 Reporter:  kevin000                                      |       Owner:  somebody   
     Type:  defect                                        |      Status:  new        
 Priority:  normal                                        |   Milestone:  Unscheduled
Component:  numpy.core                                    |     Version:  devel      
 Keywords:  recarray setfield object array runtime error  |  
----------------------------------------------------------+-----------------
 Using a recarray with member assignment fails if any column uses the
 object data type.  I don't understand why this fails, especially since the
 dictionary style assignment works.


 # Brief example showing what recarray assignments succeed or fail
 import numpy as np

 # recarray with integer datatypes
 dt = np.dtype([('foo', 'i8'), ('bar', 'i8')])
 r = np.zeros((1,3), dtype=dt).view(np.recarray)
 r['foo'] = np.array([1, 2, 3])      # OK
 r.foo = np.array([1, 2, 3])         # OK

 # recarray with an object datatype
 dt = np.dtype([('foo', 'i8'), ('bar', 'O8')])
 r = np.zeros((1,3), dtype=dt).view(np.recarray)
 r['foo'] = np.array([1, 2, 3])      # OK
 r.foo = np.array([1, 2, 3])         # RuntimeError


 For the relevant C code search for "cannot call setfield on an object
 array" in this file:

 https://github.com/numpy/numpy/blob/master/numpy/core/src/multiarray/methods.c

 Thanks!

 Kevin

-- 
Ticket URL: <http://projects.scipy.org/numpy/ticket/2006>
NumPy <http://projects.scipy.org/numpy>
My example project