Hi all, I'm wondering if the following difference in behavior of object arrays should be considered a bug. Let a and b be:
In [21]: a = [0,1] In [22]: b = [ None, None] If we concatenate a with an empty list, it works: In [23]: numpy.concatenate(([],a)) Out[23]: array([0, 1]) But not so for b: In [24]: numpy.concatenate(([],b)) --------------------------------------------------------------------------- exceptions.ValueError Traceback (most recent call last) /home/fperez/<ipython console> ValueError: 0-d arrays can't be concatenated This behavior changed recently (it used to work with r2788), and I realize it's probably part of all the reworkings of the object arrays which have been discussed on the list, and all of whose details I have to admit I haven't followed. But this behavior strikes me as a bit inconsistent, since concatenation with a non-empty object array works fine: In [26]: numpy.concatenate(([None],b)) Out[26]: array([None, None, None], dtype=object) This is biting us in some code which keeps object arrays, because when operations of the kind N.concatenate((some_list_of_objects[:nn],other_object_array)) are taken and nn happens to be 0, the code just explodes. In our case, the variable nn is a runtime computed quantity that comes from a numerical algorithm, for which 0 is a perfectly reasonable value. Are we just misusing things and is there a reasonable alternative, or should this be considered a numpy bug? The r2788 behavior was certainly a lot less surprising as far as our code was concerned. I realize that one alternative is to wrap everything into arrays: N.concatenate((N.asarray(some_list_of_objects[:nn]),other_object_array)) Is this the only solution moving forward, or could the previous behavior be restored without breaking other areas of the new code/design? Thanks for any input, f ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Numpy-discussion mailing list Numpy-discussion@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/numpy-discussion
