[Tutor] Removing duplicates in a list with a fixed length of items in the list.

[Adam Cripps]

On 1/11/07, Adam Cripps <kabads at gmail.com> wrote:
> On 1/11/07, Kent Johnson <kent37 at tds.net> wrote:
> > Adam Cripps wrote:
> > > I have a list which comprises of simple random arithmetic problems for
> > > teachers to give to their pupils. This list must be a set length (if
> > > the teacher asks for 10 questions, they should get 10 questions), but
> > > should not have any duplicates.
> > >
> > > I've seen the use of sets, but this reduces the size of the list, when
> > > I have to have a fixed length.
> > >
> > > Is there a quick way of checking if a string is already within a list
> > > without iterating over the items of the list (which will slow the
> > > application down slightly)?
> >
> > Hmm. If you are trying to pick 10 elements at random from a larger list,
> > use random.sample(problems, 10)
> >
> > If for some reason that doesn't work for you (maybe you are creating
> > problems on the fly?) you could build a set in a loop, adding items
> > until it is the size you want:
> > problemSet = set()
> > while len(problemSet) < 10:
> >    # do something to add a (possibly) new problem to the set
> >
>

I'm creating them on the fly - so this suggestion seems to be the
sensible way forward.

I've not worked with Sets before but will give it a go. Is there a way
of turning the Set back to a list?

TIA
Adam
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