On Sun, Feb 28, 2010 at 01:05:15PM +0200, Pauli Virtanen wrote: > su, 2010-02-28 kello 10:25 +0100, Gael Varoquaux kirjoitti: > [clip] > > The problem is that ndarrays cannot be compared. So I have tried to > > override the 'cmp' in the 'sorted' function, however I am comparing > > fairly complex objects, and I am having a hard time predicting wich > > member of the object will contain the array.
> I don't understand what "predicting which member of the object" means? > Do you mean that in the array, you have classes that contain ndarrays as > their attributes, and the classes have __cmp__ implemented? Well, I might not have to compare ndarrays, but fairly arbitrary structures (dictionnaries, classes and lists) as I am dealing with semi-structured data coming from a stack of unorganised experimental data. Python has some logic for comparing these structures by comparing their members, but if these are ndarrays, I am back to my original problem. > If not, can you tell why > def xcmp(a, b): > a_nd = isinstance(a, ndarray) > b_nd = isinstance(b, ndarray) > if a_nd and b_nd: > pass # compare ndarrays in some way > elif a_nd: > return 1 # sort ndarrays first > elif b_nd: > return -1 # sort ndarrays first > else: > return cmp(a, b) # ordinary compare > does not work? Because I have things like lists of ndarrays, on which this fails. If I could say: use recursively xcmp instead of cmp for this sort, it would work, but the only way I can think of doing this is by monkey-patching temporarily __builtins__.cmp, which I'd like to avoid, as it is not thread safe. Cheers, Gaël _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
