[GitHub] [spark] BeishaoCao-db commented on a diff in pull request #40907: [SPARK-43270][PYTHON] Implement `__dir__()` in `pyspark.sql.dataframe.DataFrame` to include columns

["BeishaoCao-db (via GitHub)" <gi...@apache.org>]

BeishaoCao-db commented on code in PR #40907:
URL: https://github.com/apache/spark/pull/40907#discussion_r1179547179


##########
python/pyspark/sql/dataframe.py:
##########
@@ -3008,6 +3008,34 @@ def __getattr__(self, name: str) -> Column:
         jc = self._jdf.apply(name)
         return Column(jc)
 
+    def __dir__(self) -> List[str]:
+        """
+        Examples
+        --------
+        >>> from pyspark.sql.functions import lit
+
+        Create a dataframe with a column named 'id'.
+
+        >>> df = spark.range(3)
+        >>> [attr for attr in dir(df) if attr[0] == 'i'][:7] # Includes column id
+        ['id', 'inputFiles', 'intersect', 'intersectAll', 'isEmpty', 'isLocal', 'isStreaming']
+
+        Add a column named 'i_like_pancakes'.
+
+        >>> df = df.withColumn('i_like_pancakes', lit(1))
+        >>> [attr for attr in dir(df) if attr[0] == 'i'][:7] # Includes columns i_like_pancakes, id
+        ['i_like_pancakes', 'id', 'inputFiles', 'intersect', 'intersectAll', 'isEmpty', 'isLocal']
+
+        Try to add an existed column 'inputFiles'.
+
+        >>> df = df.withColumn('inputFiles', lit(2))
+        >>> [attr for attr in dir(df) if attr[0] == 'i'][:7] # Doesn't duplicate inputFiles
+        ['i_like_pancakes', 'id', 'inputFiles', 'intersect', 'intersectAll', 'isEmpty', 'isLocal']
+        """
+        attrs = list(super().__dir__())
+        attrs.extend(attr for attr in self.columns if attr not in attrs)

Review Comment:
   I don't see the point of using hasattr: our implementation about `__getattr__ `check the columns exist or not and we still  need to check that `attr not in attrs`



##########
python/pyspark/sql/dataframe.py:
##########
@@ -3008,6 +3008,34 @@ def __getattr__(self, name: str) -> Column:
         jc = self._jdf.apply(name)
         return Column(jc)
 
+    def __dir__(self) -> List[str]:
+        """
+        Examples
+        --------
+        >>> from pyspark.sql.functions import lit
+
+        Create a dataframe with a column named 'id'.
+
+        >>> df = spark.range(3)
+        >>> [attr for attr in dir(df) if attr[0] == 'i'][:7] # Includes column id
+        ['id', 'inputFiles', 'intersect', 'intersectAll', 'isEmpty', 'isLocal', 'isStreaming']
+
+        Add a column named 'i_like_pancakes'.
+
+        >>> df = df.withColumn('i_like_pancakes', lit(1))
+        >>> [attr for attr in dir(df) if attr[0] == 'i'][:7] # Includes columns i_like_pancakes, id
+        ['i_like_pancakes', 'id', 'inputFiles', 'intersect', 'intersectAll', 'isEmpty', 'isLocal']
+
+        Try to add an existed column 'inputFiles'.
+
+        >>> df = df.withColumn('inputFiles', lit(2))
+        >>> [attr for attr in dir(df) if attr[0] == 'i'][:7] # Doesn't duplicate inputFiles
+        ['i_like_pancakes', 'id', 'inputFiles', 'intersect', 'intersectAll', 'isEmpty', 'isLocal']
+        """
+        attrs = list(super().__dir__())

Review Comment:
   1. we use set and remove the check, return sorted list
   2. still use the list, return sorted list
   
   I submit 2 commits for each of them, which one do you prefer?



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