Plotting a ROC curve in scikit yields only 3 points

I had the same problem with a different example. The mistake I made was to input the outcomes for a given threshold and not the probabilities in the argument y_score of roc_curve. It also gives a plot with three points but it is a mistake !

The number of points depend on the number of unique values in the input. Since the input vector has only 2 unique values, the function gives correct output.

I ran into same problem, and after reading the documentaion carefully I realized that the mistake is in:

probas_ = model.predict_log_proba(X)

Although, there were hints pointed by others by checking the uniqueness. It should be instead:

probas_ = model.decisions(X)