I have a list predictions [0, 1, 0 , ....] and a list outcome [ 0, 0, 1, ...]. I want to create a list of all predictions where outcome is 1
I tried:
filtered_list = [predictions[i] for i in predictions if outcome[i]==1]
Unfortunately that resulted in an empty list.
What am I doing wrong? EDIT: I think I fixed it - not sure, as I have not been able to audit the result
filtered_list = [i for i in predictions if outcome[i]==1]
If predictions and outcomes are of the same length, you can use zip()
[prediction for prediction, outcome in zip(predictions, outcome) if outcome==1]
Otherwise, just change zip() for the function zip_longest() of the itertools module.
Use enumerate:
[i for c,i in enumerate(predictions) if outcome[c]==1]
Right now you are indexing by the values and not the indices and that is why it is not working
i is an actual prediction, not an index. You need to iterate over the indices to use i with both lists.
# Working, but meh. See below
filtered_list = [predictions[i] for i in range(len(predictions))
if outcome[i] == 1]
However, a better solution is to iterate over the elements of both lists in parallel, avoiding indices altogether.
filtered_list = [pred for pred, outcome in zip(predictions, outcomes)
if outcome == 1]
predictionsis a list of 0s and 1s, you are only looking atoutcome[0]andoutcome[1], not the outcome of a prediction.