LightGBM with the Focal Loss for imbalanced datasetsThe Focal loss (hereafter FL) was introduced by Tsung-Yi Lin et al., in their 2018 paper “Focal Loss for Dense Object Detection”[1]. It is designed to address scenarios with extreme imbalanced classes, such as one-stage object detection where the imbalance between foreground and background classes can be, for example, 1:1000. In this post I will show how to code the FL for LightGBM[2](hereafter LG
