"Was_impossible" meaning

[mfahadakbar]

Description

What does "was_impossible = False" mean in the output of the predict method? I tried to find it out through documentation, but couldn't find any explanation. Thank you

[NicolasHug]

This happens when the algorithm isn't able to output a prediction, for example when the user or the item isn't part of the training set. You'll find more details of its usage throughout the code: https://github.com/NicolasHug/Surprise/search?q=PredictionImpossible

When was_impossible = True, the prediction is set to the global mean rating of the training set.