论文标题
多个操作点的分层分类
Hierarchical classification at multiple operating points
论文作者
论文摘要
许多分类问题考虑构成层次结构的类。尽管不确定在细元水平上,但了解该层次结构的分类器可能能够在粗糙的水平上做出自信的预测。尽管通常可以使用推理时阈值来改变预测的粒度,但大多数当代工作仅考虑叶子节点的预测,几乎没有先前的工作比较了多个操作点的方法。我们提出了一种有效的算法,以产生为层次结构中每个类别分配分数的任何方法的工作特性曲线。应用此技术评估现有方法表明,自上而下的分类器在整个操作范围内由幼稚的扁平软效果分类器主导。我们进一步提出了两个新的损失功能,并表明结构化铰链损耗的软变量能够显着胜过平坦的基线。最后,我们研究了自上而下的分类器的准确性差,并证明它们在看不见的课程中的表现相对良好。代码可在https://github.com/jvlmdr/hiercls在线获得。
Many classification problems consider classes that form a hierarchy. Classifiers that are aware of this hierarchy may be able to make confident predictions at a coarse level despite being uncertain at the fine-grained level. While it is generally possible to vary the granularity of predictions using a threshold at inference time, most contemporary work considers only leaf-node prediction, and almost no prior work has compared methods at multiple operating points. We present an efficient algorithm to produce operating characteristic curves for any method that assigns a score to every class in the hierarchy. Applying this technique to evaluate existing methods reveals that top-down classifiers are dominated by a naive flat softmax classifier across the entire operating range. We further propose two novel loss functions and show that a soft variant of the structured hinge loss is able to significantly outperform the flat baseline. Finally, we investigate the poor accuracy of top-down classifiers and demonstrate that they perform relatively well on unseen classes. Code is available online at https://github.com/jvlmdr/hiercls.