iterating in reverse
jbperez808 at yahoo.com
Fri Jan 17 09:54:04 CET 2003
Chad Netzer <cnetzer at mail.arc.nasa.gov> wrote in message news:<mailman.1042765110.10945.python-list at python.org>...
> FWIW. list.reverse() is often not too bad since it only has to do the
> work of reversing the list indices in memory, not copying the actual
> objects themselves. Iterating backwards does save an O(N) operation,
> but for small lists, list.reverse() is likely faster.
I need to iterate using for in both the original order and
in reverse depending on the situation.
The main thing that bugs me is that I have to choose between
storing 2 copies of the same data (one reversed, the other not)
or I have to do a couple of reverse()s each time (to undo the
transformation) I need to access the list in reverse. The former
is wasteful of space, the latter of performance.
More information about the Python-list