$($AUC$-$PR and AP$)$ We have not discussed the details of how the AUC$-$PR measurement$$is calculated. For a binary classification task, we assume that every example$$x has a score f $($x$),$ and sort the test examples into descending order of these scores.$$Then$,$ for every example, we set the classification threshold as the current example$$s$$score $($i$.$e$.,$ only this example and the examples before it are classified as positive$).$ A$$pair of precision and recall values are computed at this threshold. The PR curve is$$drawn by connecting nearby points using line segments. Then AUC$-$PR is the area$$under the PR curve.