On 31 May 2010 20:19, Payal <payal-pyt...@scriptkitchen.com> wrote: > Hi, > I am trying to learn Python (again) and have some basic doubts which I > hope someone in the list can address. (English is not my first language and > I > have no CS background except I can write decent shell scripts) > > Welcome (back) to the Python-List!
> When I type help(something) e.g. help(list), I see many methods like, > __methodname__(). Are these something special? They're very special. You can think of them as "Python internal functions", and are called internally by other functions. > How do I use them and why > put "__" around them? > You call them as if they were any other function. 99% of the time though, you don't need to call them, as there are better, cleaner ways. > > One more simple query. Many times I see something like this, > | D.iteritems() -> an iterator over the (key, value) items of D > What is this iterator they are talking about <...> > See http://docs.python.org/library/stdtypes.html#iterator-types . Just a peek, nothing big. > and how do I use these > You can use iterators by ... iterating through the items! Like this: >>> for i in [1, 3, 6, 10, 15]: ... print i ... 1 3 6 10 15 and, in your specific example: >>> x = {1: 2, 3: 4} >>> for key, value in x.iteritems(): ... print key, "->", value ... 1 -> 2 3 -> 4 > methods because simly saying D.iteritems() does not > work?<http://mail.python.org/mailman/listinfo/python-list> It does work - it returns you an iterator you can use later: >>> x_items = x.iteritems() >>> for k, v in x_items: ... print k + v ... 3 7 Have fun with Python! Cheers, Xav
-- http://mail.python.org/mailman/listinfo/python-list
