qq_23904809的博客

报错信息：只是将value赋值给了原数据集df的一个副本，并没有改变df的值SettingWithCopyWarning:A value is trying to be set on a copy of a slice from a DataFrame.

cannot import name ‘_to_object_array’ from ‘sklearn.utils’解决办法：重启anaconda解决参考的文章链接：click

pandas 报错“TypeError: reduction operation 'argmax' not allowed for this dtype”解决办法问题现象问题原因解决办法问题现象执行语句crime.idxmax()报错，报错“TypeError: reduction operation ‘argmax’ not allowed for this dtype”数据框crime：问题原因由打印数据框crime可知，列Year并非数据框crime的索引idxmax() 返回的是最

select classId, name, score, dense_rank() over (partition by classId order by score) as rankingfrom tablewhere ranking<=3;别名ranking用在where子句后会报错“列名ranking无效”，其原因是：SQL的执行顺序是先where后select详细可参考这篇博客：https://blog.youkuaiyun.com/Jin.