“…However, they usually assume that the training and testing data is balanced. In practice, training or testing data appears to be long-tailed, e.g., there exist few samples for rare diseases in medical diagnosis [19,35,36,39,42,45] or endangered animals in species classification [5,31,37]. As mentioned by [32], the case becomes even worse in weakly and semi-supervised learning scenarios [10,20,27,31,33,34,38,43,44].…”