> To be honest I'm relatively new to Python, so I don't know too much
> about how all the loop constructs work and how they differ to other
> languages. I'm building an app in Django and this data is coming out
> of a database and it looks like what I put up there!
>
> This was my (failed) attempt:
>
> predictions = Prediction.objects.all()
> scores = []
> for prediction in predictions:
> i = [prediction.predictor.id, 0]
> if prediction.predictionscore:
> i[1] += int(prediction.predictionscore)
> scores.append(i)
>
> I did have another loop in there (I'm fairly sure I need one) but that
> didn't work either. I don't imagine that snippet is very helpful,
> sorry!
It is helpful because it tells us what your actual data looks like.
What you need is to get a list of (predictor, score)-pairs. These you should
be able to get like this:
l = [(p.predictor.id, p.predictionscore) for p in predictions]
Now you need to sort this list - because in the next step, we will aggregate
the values for each predictor.
result = []
current_predictor = None
total_sum = 0
for predictor, score in l:
if predictor != current_predictor:
# only if we really have a current_predictor,
# the non-existent first one doesn't count
if current_predictor is not None:
result.append((predictor, total_sum))
total_sum = 0
current_predictor = predictor
total_sum += score
That should be roughly it.
Diez
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