On 2008-12-10 16:40, Luis Zarrabeitia wrote: > Quoting Rasmus Fogh <[EMAIL PROTECTED]>: >> Rhamphoryncus wrote: >>> You grossly overvalue using the "in" operator on lists. >> Maybe. But there is more to it than just 'in'. If you do: >>>>> c = numpy.zeros((2,)) >>>>> ll = [1, c, 3.] >> then the following all throw errors: >> 3 in ll, 3 not in ll, ll.index(3), ll.count(3), ll.remove(3) >> c in ll, c not in ll, ll.index(c), ll.count(c), ll.remove(c) >> >> Note how the presence of c in the list makes it behave wrong for 3 as >> well. > > I think I lost the first messages on this thread, but... Wouldn't be easier to > just fix numpy? I see no need to have the == return anything but a boolean, at > least on Numpy's case. The syntax 'a == b' is an equality test, not a detailed > summary of why they may be different, and (a==b).all() makes no little sense > to > read unless you know beforehad that a and b are numpy arrays. When I'm > comparing > normal objects, I do not expect (nor should I) the == operator to return an > attribute-by-attribute summary of what was equal and what wasn't. > > Why is numpy's == overloaded in such a counter intuitive way? I realize that > an > elementwise comparison makes a lot of sense, but it could have been done > instead > with a.compare_with(b) (or even better, a.compare_with(b, epsilon=e)). No > unexpected breakage, and you have the chance of specifying when you consider > two > elements to be equal - very useful.
Rich comparisons were added to Python at the request of the Numeric (now numpy) developers and they have been part of Python a Numeric for many many years. I don't think it's likely they'll change things back to the days of Python 1.5.2 ;-) > Even the transition itself could be done without breaking much code... Make > the > == op return an object that wraps the array of bools (instead of the array > itself), give it the any() and all() methods, and make __nonzero__/__bool__ > equivalent to all(). That would cause a lot of confusion on its own, since such an object wouldn't behave in the same way as say a regular Python list (bool([0]) == True). -- Marc-Andre Lemburg eGenix.com Professional Python Services directly from the Source (#1, Dec 10 2008) >>> Python/Zope Consulting and Support ... http://www.egenix.com/ >>> mxODBC.Zope.Database.Adapter ... http://zope.egenix.com/ >>> mxODBC, mxDateTime, mxTextTools ... http://python.egenix.com/ ________________________________________________________________________ 2008-12-02: Released mxODBC.Connect 1.0.0 http://python.egenix.com/ ::: Try our new mxODBC.Connect Python Database Interface for free ! :::: eGenix.com Software, Skills and Services GmbH Pastor-Loeh-Str.48 D-40764 Langenfeld, Germany. CEO Dipl.-Math. Marc-Andre Lemburg Registered at Amtsgericht Duesseldorf: HRB 46611 http://www.egenix.com/company/contact/ -- http://mail.python.org/mailman/listinfo/python-list
