[GitHub] [superset] serenajiang commented on a change in pull request #15975: fix: eliminate cartesian product columns in pivot operator

[GitBox <gi...@apache.org>]

serenajiang commented on a change in pull request #15975:
URL: https://github.com/apache/superset/pull/15975#discussion_r680088605



##########
File path: superset/utils/pandas_postprocessing.py
##########
@@ -264,6 +264,17 @@ def pivot(  # pylint: disable=too-many-arguments
     #  Remove once/if support is added.
     aggfunc = {na.column: na.aggfunc for na in aggregate_funcs.values()}
 
+    # When dropna = False, the pivot_table function will calculate cartesian-product
+    # for MultiIndex.
+    # https://github.com/apache/superset/issues/15956
+    # https://github.com/pandas-dev/pandas/issues/18030
+    series_set = set()
+    lst_to_str: Callable[[List[Any]], str] = lambda lst: "_".join(str(_) for _ in lst)

Review comment:
       minor nit - I think you could just replace calls of this this with `str()`.




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