Efficient Prequential AUC-PR Computation.

When dealing with classification problems for data streams, we often need to compute the classification metrics in a prequential manner. The Area Under the Precision-Recall Curve (AUC-PR) metric is extensively used in imbalanced classification scenarios, where the negative class outnumbers the positive one. Despite its advantages, it may be computationally expensive to recompute that metric every time a new test instance becomes available. In this work, we present an efficient algorithm to compute the AUC-PR in a prequential way. Our proposed algorithm uses a self-balancing binary search tree to avoid the need to reorder the data when updating the AUC-PR value with the most recent data. Our experiments take into consideration six well-known, publicly available stream-based datasets. Our experiments show that our approach can be up to 13 times faster and use 12 times less energy than the traditional batch approach when considering a window of size 1,000.