Re: [Python-Dev] list.discard? (Re: dict.discard)
When I want to remove something from a list I typically write: while x in somelist: somelist.remove(x) An O(n) version of removeall: somelist[:] = [e for e in somelist if e != x] Raymond ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] list.discard? (Re: dict.discard)
Greg Or maybe remove() should just do nothing if the item is not Greg found. If that's the case, I'd argue that dict.remove and set.remove should behave the same way, making .discard unnecessary. OTOH, perhaps lists should grow a .discard method. Skip ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] list.discard? (Re: dict.discard)
Greg Ewing wrote: Actually I'd like this for lists. Often I find myself writing if x not in somelist: somelist.remove(x) A single method for doing this would be handy, and more efficient. there is a single method that does this, of course, but you have to sprinkle some sugar on it: try: somelist.remove(x) except ValueError: pass /F ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] list.discard? (Re: dict.discard)
[EMAIL PROTECTED] wrote: It's obvious for sets and dictionaries that there is only one thing to discard and that after the operation you're guaranteed the key no longer exists. Would you want the same semantics for lists or the semantics of list.remove where it only removes the first instance? In my use cases I usually know that there is either zero or one occurrences in the list. But maybe it would be more useful to have a remove_all() method, whose behaviour with zero occurrences would just be a special case. Or maybe remove() should just do nothing if the item is not found. I don't think I've ever found getting an exception from it to be useful, and I've often found it a nuisance. What experiences have others had with it? -- Greg ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
[Python-Dev] list.discard? (Re: dict.discard)
Gustavo Niemeyer wrote: print set.discard.__doc__ Remove an element from a set if it is a member. Actually I'd like this for lists. Often I find myself writing if x not in somelist: somelist.remove(x) A single method for doing this would be handy, and more efficient. -- Greg ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] list.discard? (Re: dict.discard)
On Thursday 21 September 2006 20:21, Greg Ewing wrote: if x not in somelist: somelist.remove(x) I'm just guessing you really meant if x in somelist. ;-) -Fred -- Fred L. Drake, Jr. fdrake at acm.org ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] list.discard? (Re: dict.discard)
Greg Ewing [EMAIL PROTECTED] wrote: Gustavo Niemeyer wrote: print set.discard.__doc__ Remove an element from a set if it is a member. Actually I'd like this for lists. Often I find myself writing if x not in somelist: somelist.remove(x) A single method for doing this would be handy, and more efficient. A marginal calling time improvement; but we are still talking linear time containment test. I'm -0, if only because I've never really found the need to use list.remove(), so this API expansion doesn't feel necessary to me. - Josiah ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] list.discard? (Re: dict.discard)
Greg Actually I'd like [discard] for lists. It's obvious for sets and dictionaries that there is only one thing to discard and that after the operation you're guaranteed the key no longer exists. Would you want the same semantics for lists or the semantics of list.remove where it only removes the first instance? When I want to remove something from a list I typically write: while x in somelist: somelist.remove(x) not if as in your example. Skip ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] list.discard? (Re: dict.discard)
Fred L. Drake, Jr. wrote: On Thursday 21 September 2006 20:21, Greg Ewing wrote: if x not in somelist: somelist.remove(x) I'm just guessing you really meant if x in somelist. ;-) No you aren't, that's clearly an *informed* guess. regards Steve -- Steve Holden +44 150 684 7255 +1 800 494 3119 Holden Web LLC/Ltd http://www.holdenweb.com Skype: holdenweb http://holdenweb.blogspot.com Recent Ramblings http://del.icio.us/steve.holden ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
