iloc loc ix: https://www.jb51.net/article/141665.htm
read_csv/table: https://blog.csdn.net/shener_m/article/details/81047669
concatenate:https://blog.csdn.net/vitaminc4/article/details/79332459?utm_source=blogxgwz0
Imputer=http://www.dataivy.cn/blog/3-1-%E6%95%B0%E6%8D%AE%E6%B8%85%E6%B4%97%EF%BC%9A%E7%BC%BA%E5%A4%B1%E5%80%BC%E3%80%81%E5%BC%82%E5%B8%B8%E5%80%BC%E5%92%8C%E9%87%8D%E5%A4%8D%E5%80%BC%E7%9A%84%E5%A4%84%E7%90%86-2%E4%BB%A3%E7%A0%81/#more-1075
numpy.ravel() vs numpy.flatten():https://blog.csdn.net/lanchunhui/article/details/50354978