En Thu, 12 Apr 2007 19:38:55 -0300, Scott <[EMAIL PROTECTED]> escribió:
> List's and Tuple's > I don't see the distinction between the two. I mean, I understand that a > list is mutable and a tuple is immutable. > The thing that I dont understand about them is what, besides that, > seperates > the two. Perhaps this old post from 2001 can explain a bit: http://groups.google.com/group/comp.lang.python/browse_thread/thread/7eaf9fe92b4c7e47/#78e78f179a893526 Or perhaps this one from 1998: http://groups.google.com/group/comp.lang.python/browse_thread/thread/358ef18309812fbb/14199e16f119a020 > Now you can add to a list, but not a tuple so: > >>>> my_list.append(my_tuple) #or extend for that matter right? > [1, 2, 3, 4, 5, 6, (1, 2, 3, 4, 5, 6)] > > Is that pretty much accurate? And which is better on resources....I'm > guessing a tuple seeing as it doesn't change. Yes. Tuples are immutable - once created, they can't change. > And the last example brings up another question. What's the deal with a > tupple that has a list in it such as: > >>>> my_tupple = (1, 2, 3, 4, 5, [6, 7, 8, 9]) > > Now I read somewhere that you could change the list inside that tupple. > But > I can't find any documentation that describes HOW to do it. The only > things > I CAN find on the subject say, "Don't do it because its more trouble than > it's worth." But that doesn't matter to me, because I want to know > everything. The *contents* of the list can be changed, but not the list itself: my_tupple[5].append(10) del my_tupple[5][2] my_tupple will always contain *that* list, whatever you put inside it. (Do not confuse the list object -a container- with the objects contained inside it) > Now there comes append. I read everywhere that append only add's 1 > element > to the end of your list. But if you write: >>>> my_list = [1, 2, 3, 4, 5, 6] my_list contains 6 elements: len(my_list)==6 >>>> my_list.append([7, 8, 9, 10]) >>>> my_list > [1, 2, 3, 4, 5, 6, [7, 8, 9, 10]] my_list now contains 7 elements: len(my_list)==7 Its seventh element happens to be a list itself, but that doesn't matter: my_list sees it as a single object like any other. > Is that because list's, no matter what they contain, are counted as 1 > element? Exactly. Lists or whatever object you want, if you append it to my_list, my_list grows by one element. It doesn't care *what* it is - it's a new element. > And how would you sort the list that's in the list? I guess that goes in > conjunction with the section above, but still: >>>> my_list = [6, 4, 3, 5, 2, 1] >>>> my_list.append([7, 9, 8, 10]) >>>> my_list.sort() >>>> my_list > [1, 2, 3, 4, 5, 6, [7, 9, 8, 10]] To sort my_list, you call the sort method on my_list: my_list.sort() To sort "the list that's in the list", i.e. my_list[6], you call the sort method on "the list that's in the list": my_list[6].sort() > This is, again, something I'm finding nothing on. You call a method on any object using any_object.method_name(some, parameters, may_be=required) any_object may be any arbitrary expression, like my_list[6] above > Maybe I'm just not looking in the right spots. The only things I have as > learning aids are: this newsgroup ;p, http://diveintopython.org, > http://python.org/, Beggining Python: From Novice to Professional, and > (now > don't laugh) Python for Dummies. That's fine - just keep programming, and have fun. -- Gabriel Genellina -- http://mail.python.org/mailman/listinfo/python-list
