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From Manish Tripathi <tr.man...@gmail.com>
Subject Negative values of predictions in ALS.tranform
Date Thu, 15 Dec 2016 22:20:54 GMT
Hi

ran the ALS model for implicit feedback thing. Then I used the .transform
method of the model to predict the ratings for the original dataset. My
dataset is of the form (user,item,rating)

I see something like below:

predictions.show(5,truncate=False)


Why is the last prediction value negative ?. Isn't the transform method
giving the prediction(probability) of seeing the rating as 1?. I had counts
data for rating (implicit feedback) and for validation dataset I binarized
the rating (1 if >0 else 0). My training data has rating positive (it's
basically the count of views to a video).

I used following to train:

* als = ALS(rank=x, maxIter=15, regParam=y, implicitPrefs=True,alpha=40.0)*

*                model=als.fit(self.train)*

What does negative prediction mean here and is it ok to have that?
ᐧ

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