“…Its mathematical and physical meaning is clear, and its calculation is simple (Deng, 1985). At present, grey relational degree has been widely used in natural science, social science and engineering management fields (Liu, 2017), such as the analysis of crop yield affecting factors (Chen et al , 2020; Li et al , 2019), flood identification and flood forecast (Feng et al , 2021), evaluation of multilevel dispatching rules in wafer fabrication (Yee et al , 2021), evaluation of technological innovation ability in universities (Sang et al , 2019), hospital readmission prediction based on improved feature selection (Miswan et al , 2021), China's overcapacity industry evaluation with mixed attributes (Hao et al , 2021), decision-making in manufacturing industry upgrading (Yu et al , 2020), hyperspectral estimation of soil organic matter content (Cao et al , 2021) and so on. With the deepening of grey relational analysis, based on the Deng's relational degree model, many scholars put forward B-type relational degree (Wang, 1989), C-type relational degree (Wang et al , 1999), T-type relational degree (Tang, 1995), slope relational degree (Dang, 1994), absolute relational degree and relative relational degree (Liu et al , 2006), similarity relational degree and proximity relational degree (Liu et al , 2011), comprehensive distance relational degree (Cao et al , 2020) and so on.…”