AssertionError：所有exprs都应该是Column

Question

我加入两个PySpark DataFrames如下：

exprs = [max(x) for x in ["col1","col2"]]
df = df1.union(df2).groupBy(['campk', 'ppk']).agg(*exprs)

但是我收到了这个错误：

AssertionError: all exprs should be Column

有什么问题？

Answer 1

exprs = [max(x) for x in ["col1","col2"]]

将返回具有最大ASCII值的字符，即['o', 'o']

引用正确的max可行：

>>> from pyspark.sql import functions as F
>>> exprs = [F.max(x) for x in ["col1","col2"]]
>>> print(exprs)
[Column<max(col1)>, Column<max(col2)>]