[GitHub] [spark] itholic commented on a diff in pull request #42787: [SPARK-43241][PS] `MultiIndex.append` not checking names for equality

["itholic (via GitHub)" <gi...@apache.org>]

itholic commented on code in PR #42787:
URL: https://github.com/apache/spark/pull/42787#discussion_r1315254128


##########
python/pyspark/pandas/indexes/base.py:
##########
@@ -1917,18 +1917,12 @@ def append(self, other: "Index") -> "Index":
         sdf_other = other._internal.spark_frame.select(other._internal.index_spark_columns)
         sdf_appended = sdf_self.union(sdf_other)
 
-        # names should be kept when MultiIndex, but Index wouldn't keep its name.
-        if isinstance(self, MultiIndex):
-            index_names = self._internal.index_names
-        else:
-            index_names = None
-
         internal = InternalFrame(
             spark_frame=sdf_appended,
             index_spark_columns=[
                 scol_for(sdf_appended, col) for col in self._internal.index_spark_column_names
             ],
-            index_names=index_names,
+            index_names=None,

Review Comment:
   We can simply set the `index_names` to `None` to follow the behavior of Pandas, since Pandas doesn't keep the name of `MultiIndex` when computing the `append` from Pandas 2.0.0. (See https://github.com/pandas-dev/pandas/pull/48288 more detail)
   
   cc @zhengruifeng @HyukjinKwon as CI passed.



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