[Tutor] nested loops

[Danny Yoo]

On Mon, 22 Aug 2005, Kent Johnson wrote:

> > Is there any way more efficient for run a nested loop?
> >
> > ------
> > for a in list_a:
> >     for b in list_b:
> >         if a == b: break

Hi Jonas,

Depends on what we're trying to do.  Is it necessary to have a nested loop
here?  What kind of problem is this trying to solve?

If the question is: "are any elements in list_a shared in list_b?", then
yes, we can avoid nested loops altogether.  If we're concerned about
efficiency, we can take advanatage of dictionaries, or use something like
the 'set' data structure.

    http://www.python.org/doc/lib/module-sets.html