Thanks, this is not too much information at all. I am always happy with depth.
-c On 3/15/07, Dave Kuhlman <[EMAIL PROTECTED]> wrote: > On Thu, Mar 15, 2007 at 03:35:27PM +0100, Rikard Bosnjakovic wrote: > > On 3/15/07, Clay Wiedemann <[EMAIL PROTECTED]> wrote: > > > If doing a loop, how can one skip forward a specific amount randomly > > > determined within the loop? > > > > y = 0 > > while y < HEIGHT: > > linewidth = random(3, 9) > > # drawlines etc > > y += linewidth > > > > The reason why you cannot alter the for-variable beats me, though. > > The while-statement looks like a good solution to me. > > Two additional points: > > 1. You can alter the for-variable, *but* each time you go to the > top of the for-loop, that variable is set to the next item from > the iterator, wiping out any alteration. Because of this, you > can modify and use that variable within the loop body without > having to worry about messing up the loop sequence. What Clay > wants to do is mess with the sequencing of items in the loop. > > 2. The reason that modifying the for-variable does not change the > sequence of objects processed by the loop is that the > for-statement is generating a sequence of objects from an > iterator. In this case the range function creates a list, which > the for-statement turns into an iterator. > > You don't even *want* to give Clay what he is asking for. He asked > about being able to jump forward in the loop or sequence. If you > were able to give him that one, he would come back and ask whether > he could jump *backward* in the loop. > > For more on iterators, see "Iterator types" at > http://docs.python.org/lib/typeiter.html. Also see the "iter" > function in "Built-in functions": > http://docs.python.org/lib/built-in-funcs.html. > > You can think of the following: > > def test2(): > for item in range(4): > print item > > as syntactic sugar for this: > > def test1(): > myrange = range(4) > myiter = iter(myrange) > try: > while True: > item = myiter.next() > print item > except StopIteration, e: > pass > > Hoping this is not TMI (too much information), but sometimes it > helps to understand what is going on underneath, because the for > statement and iterators are very general, powerful, > and elegant features of Python. > > Dave > > > -- > Dave Kuhlman > http://www.rexx.com/~dkuhlman > _______________________________________________ > Tutor maillist - Tutor@python.org > http://mail.python.org/mailman/listinfo/tutor > -- - - - - - - - Clay S. Wiedemann voice: 718.362.0375 aim: khlav wii: 3905 4571 6175 2469 twitter: seastokes _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor
