On Tue, 21 Oct 2014 10:55:08 +1100, Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote:
>Seymore4Head wrote: > >> For starters I would like to know if you can make a single item list >> and then turn it into a 2 item list. Is there a command for that? >> >> Do you have to know the number of items the list will have before >> making it? > >Now these are the right sort of questions that you should be asking! > >They are concrete and tightly focused, not vague and so broad that they >could mean anything, and they invite a concrete answer rather than hints. > >First question: can you take a single list item and turn it into a 2-item >list? Yes, you can, you can turn a single list item into *anything*, >including deleting it. Start with a list, and remember that lists are >indexed starting with 0: > >py> alist = [1, 2, 4, 8, 16, 32, 64] >py> alist[0] = "hello!" >py> alist[1] = ["a", "b", "c"] >py> del alist[4] >py> print(alist) >['hello!', ['a', 'b', 'c'], 4, 8, 32, 64] > > >Second question: do you need to know the number of items in a list in >advance? No. You can add additional items to an existing list with the >append() method: > >py> import random >py> alist = [] >py> while random.random() < 0.5: >... alist.append("spam") >... >py> print(alist) >['spam', 'spam'] > > >Because this is random, if you try it you will get an unpredictable number >of "spam" words in the list. About half the time it will contain no words >at all, about a quarter of the time it will contain a single word, an >eighth of the time it will contain two words, and so forth. Thanks -- https://mail.python.org/mailman/listinfo/python-list