Fig. 4

Architecture of weighted and extended isolation forest. Firstly, several sub-datasets are generated by randomly sampling from the training dataset. Secondly, all the sub-datasets are passed into the construction of the isolation trees, and the original depths of the observations in the sub-datasets are computed for each isolation tree. Thirdly, all the original depths are weighted based on the algorithm in Table 5. Finally, the anomaly score is calculated on the average depth of the weighted depths