[GitHub] [spark] zero323 commented on pull request #32431: [SPARK-35173][SQL][PYTHON] Add multiple columns adding support

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

zero323 commented on pull request #32431:
URL: https://github.com/apache/spark/pull/32431#issuecomment-1029850928


   Since we are revisiting it have a counter-proposal ‒ instead exposing new API, let's just improve UX of what we already have. For example, if we tweak `select` to support keyword arguments like this:
   
   ```patch
   diff --git a/python/pyspark/sql/dataframe.py b/python/pyspark/sql/dataframe.py
   index ee68865c98..00a7a4543e 100644
   --- a/python/pyspark/sql/dataframe.py
   +++ b/python/pyspark/sql/dataframe.py
   @@ -1941,14 +1941,18 @@ class DataFrame(PandasMapOpsMixin, PandasConversionMixin):
            return Column(jc)
    
        @overload
   -    def select(self, *cols: "ColumnOrName") -> "DataFrame":
   +    def select(self, *cols: "ColumnOrName", **acols: Column) -> "DataFrame":
            ...
    
        @overload
   -    def select(self, __cols: Union[List[Column], List[str]]) -> "DataFrame":
   +    def select(self, __cols: Union[List[Column], List[str]], **acols: Column) -> "DataFrame":
            ...
    
   -    def select(self, *cols: "ColumnOrName") -> "DataFrame":  # type: ignore[misc]
   +    def select(  # type: ignore[misc]
   +        self,
   +        *cols: "ColumnOrName",
   +        **namedCols: Column,
   +    ) -> "DataFrame":
            """Projects a set of expressions and returns a new :class:`DataFrame`.
    
            .. versionadded:: 1.3.0
   @@ -1959,6 +1963,8 @@ class DataFrame(PandasMapOpsMixin, PandasConversionMixin):
                column names (string) or expressions (:class:`Column`).
                If one of the column names is '*', that column is expanded to include all columns
                in the current :class:`DataFrame`.
   +        namedCols : :class:`Column`
   +            exprasssions select under given alaias.
    
            Examples
            --------
   @@ -1968,8 +1974,17 @@ class DataFrame(PandasMapOpsMixin, PandasConversionMixin):
            [Row(name='Alice', age=2), Row(name='Bob', age=5)]
            >>> df.select(df.name, (df.age + 10).alias('age')).collect()
            [Row(name='Alice', age=12), Row(name='Bob', age=15)]
   -        """
   -        jdf = self._jdf.select(self._jcols(*cols))
   +        >>> df.select(
   +        ...     "age",
   +        ...     name_lower=lower("name"),
   +        ...     name_upper=upper("name"),
   +        ...     age_plus_one=col("age") + 1,
   +        ... ).limit(1).collect()
   +        [Row(age=2, name_lower='alice', name_upper='ALICE', age_plus_one=3)]
   +        """
   +        if len(cols) == 1 and isinstance(cols[0], (list, tuple)):
   +            cols = cols[0]  # type: ignore[assignment]
   +        jdf = self._jdf.select(self._jcols(*cols, *[c.alias(a) for a, c in namedCols.items()]))
            return DataFrame(jdf, self.sql_ctx)
    
        @overload
   
   ```
   
   will be able to use it like this:
   
   ```
   df = spark.range(10).select(rand(42).alias("id"))
   
   df.select(
       "id", plus_one=col("id") + 1, times_two=col("id") * 2, log_id = log("id")
   ).show()
   ```


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