Summing a 2D list

[Mark]

On Jun 12, 3:45 pm, Aidan <awe... at gmail.com> wrote:
> Aidan wrote:
> > Mark wrote:
> >> John, it's a QuerySet coming from a database in Django. I don't know
> >> enough about the structure of this object to go into detail I'm
> >> afraid.
>
> >> Aidan, I got an error trying your suggestion: 'zip argument #2 must
> >> support iteration', I don't know what this means!
>
> > well, if we can create 2 iterable sequences one which contains the user
> > the other the scores, it should work
>
> > the error means that the second argument to the zip function was not an
> > iterable, such as a list tuple or string
>
> > can you show me the lines you're using to retrieve the data sets from
> > the database? then i might be able to tell you how to build the 2 lists
> > you need.
>
> wait you already did...
>
> predictions = Prediction.objects.all()
> pairs = [(p.predictor.id,p.predictionscore) for p in predictions]
>
> those 2 lines will will build a list of user/score pairs.  you can then
> replace the call to zip with pairs
>
> any luck?

Thanks Aidan, this works great!

Thanks also to everyone else, I'm sure your suggestions would have
worked too if I'd been competent enough to do them properly!