window.py

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import sys
from typing import cast, Iterable, List, Tuple, TYPE_CHECKING, Union

from pyspark import since, SparkContext
from pyspark.sql.column import _to_seq, _to_java_column

from py4j.java_gateway import JavaObject  # type: ignore[import]

if TYPE_CHECKING:
    from pyspark.sql._typing import ColumnOrName

__all__ = ["Window", "WindowSpec"]


def _to_java_cols(
    cols: Tuple[Union["ColumnOrName", List["ColumnOrName"]], ...]
) -> int:
    sc = SparkContext._active_spark_context  # type: ignore[attr-defined]
    if len(cols) == 1 and isinstance(cols[0], list):
        cols = cols[0]  # type: ignore[assignment]
    return _to_seq(sc, cast(Iterable["ColumnOrName"], cols), _to_java_column)


class Window(object):
    """
    Utility functions for defining window in DataFrames.

    .. versionadded:: 1.4

    Notes
    -----
    When ordering is not defined, an unbounded window frame (rowFrame,
    unboundedPreceding, unboundedFollowing) is used by default. When ordering is defined,
    a growing window frame (rangeFrame, unboundedPreceding, currentRow) is used by default.

    Examples
    --------
    >>> # ORDER BY date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
    >>> window = Window.orderBy("date").rowsBetween(Window.unboundedPreceding, Window.currentRow)

    >>> # PARTITION BY country ORDER BY date RANGE BETWEEN 3 PRECEDING AND 3 FOLLOWING
    >>> window = Window.orderBy("date").partitionBy("country").rangeBetween(-3, 3)
    """

    _JAVA_MIN_LONG = -(1 << 63)  # -9223372036854775808
    _JAVA_MAX_LONG = (1 << 63) - 1  # 9223372036854775807
    _PRECEDING_THRESHOLD = max(-sys.maxsize, _JAVA_MIN_LONG)
    _FOLLOWING_THRESHOLD = min(sys.maxsize, _JAVA_MAX_LONG)

    unboundedPreceding: int = _JAVA_MIN_LONG

    unboundedFollowing: int = _JAVA_MAX_LONG

    currentRow: int = 0

    @staticmethod
    @since(1.4)
    def partitionBy(*cols: Union["ColumnOrName", List["ColumnOrName"]]) -> "WindowSpec":
        """
        Creates a :class:`WindowSpec` with the partitioning defined.
        """
        sc = SparkContext._active_spark_context  # type: ignore[attr-defined]
        jspec = sc._jvm.org.apache.spark.sql.expressions.Window.partitionBy(_to_java_cols(cols))
        return WindowSpec(jspec)

    @staticmethod
    @since(1.4)
    def orderBy(*cols: Union["ColumnOrName", List["ColumnOrName"]]) -> "WindowSpec":
        """
        Creates a :class:`WindowSpec` with the ordering defined.
        """
        sc = SparkContext._active_spark_context  # type: ignore[attr-defined]
        jspec = sc._jvm.org.apache.spark.sql.expressions.Window.orderBy(_to_java_cols(cols))
        return WindowSpec(jspec)

    @staticmethod
    def rowsBetween(start: int, end: int) -> "WindowSpec":
        """
        Creates a :class:`WindowSpec` with the frame boundaries defined,
        from `start` (inclusive) to `end` (inclusive).

        Both `start` and `end` are relative positions from the current row.
        For example, "0" means "current row", while "-1" means the row before
        the current row, and "5" means the fifth row after the current row.

        We recommend users use ``Window.unboundedPreceding``, ``Window.unboundedFollowing``,
        and ``Window.currentRow`` to specify special boundary values, rather than using integral
        values directly.

        A row based boundary is based on the position of the row within the partition.
        An offset indicates the number of rows above or below the current row, the frame for the
        current row starts or ends. For instance, given a row based sliding frame with a lower bound
        offset of -1 and a upper bound offset of +2. The frame for row with index 5 would range from
        index 4 to index 7.

        .. versionadded:: 2.1.0

        Parameters
        ----------
        start : int
            boundary start, inclusive.
            The frame is unbounded if this is ``Window.unboundedPreceding``, or
            any value less than or equal to -9223372036854775808.
        end : int
            boundary end, inclusive.
            The frame is unbounded if this is ``Window.unboundedFollowing``, or
            any value greater than or equal to 9223372036854775807.

        Examples
        --------
        >>> from pyspark.sql import Window
        >>> from pyspark.sql import functions as func
        >>> from pyspark.sql import SQLContext
        >>> sc = SparkContext.getOrCreate()
        >>> sqlContext = SQLContext(sc)
        >>> tup = [(1, "a"), (1, "a"), (2, "a"), (1, "b"), (2, "b"), (3, "b")]
        >>> df = sqlContext.createDataFrame(tup, ["id", "category"])
        >>> window = Window.partitionBy("category").orderBy("id").rowsBetween(Window.currentRow, 1)
        >>> df.withColumn("sum", func.sum("id").over(window)).sort("id", "category", "sum").show()
        +---+--------+---+
        | id|category|sum|
        +---+--------+---+
        |  1|       a|  2|
        |  1|       a|  3|
        |  1|       b|  3|
        |  2|       a|  2|
        |  2|       b|  5|
        |  3|       b|  3|
        +---+--------+---+

        """
        if start <= Window._PRECEDING_THRESHOLD:
            start = Window.unboundedPreceding
        if end >= Window._FOLLOWING_THRESHOLD:
            end = Window.unboundedFollowing
        sc = SparkContext._active_spark_context  # type: ignore[attr-defined]
        jspec = sc._jvm.org.apache.spark.sql.expressions.Window.rowsBetween(start, end)
        return WindowSpec(jspec)

    @staticmethod
    def rangeBetween(start: int, end: int) -> "WindowSpec":
        """
        Creates a :class:`WindowSpec` with the frame boundaries defined,
        from `start` (inclusive) to `end` (inclusive).

        Both `start` and `end` are relative from the current row. For example,
        "0" means "current row", while "-1" means one off before the current row,
        and "5" means the five off after the current row.

        We recommend users use ``Window.unboundedPreceding``, ``Window.unboundedFollowing``,
        and ``Window.currentRow`` to specify special boundary values, rather than using integral
        values directly.

        A range-based boundary is based on the actual value of the ORDER BY
        expression(s). An offset is used to alter the value of the ORDER BY expression, for
        instance if the current ORDER BY expression has a value of 10 and the lower bound offset
        is -3, the resulting lower bound for the current row will be 10 - 3 = 7. This however puts a
        number of constraints on the ORDER BY expressions: there can be only one expression and this
        expression must have a numerical data type. An exception can be made when the offset is
        unbounded, because no value modification is needed, in this case multiple and non-numeric
        ORDER BY expression are allowed.

        .. versionadded:: 2.1.0

        Parameters
        ----------
        start : int
            boundary start, inclusive.
            The frame is unbounded if this is ``Window.unboundedPreceding``, or
            any value less than or equal to max(-sys.maxsize, -9223372036854775808).
        end : int
            boundary end, inclusive.
            The frame is unbounded if this is ``Window.unboundedFollowing``, or
            any value greater than or equal to min(sys.maxsize, 9223372036854775807).

        Examples
        --------
        >>> from pyspark.sql import Window
        >>> from pyspark.sql import functions as func
        >>> from pyspark.sql import SQLContext
        >>> sc = SparkContext.getOrCreate()
        >>> sqlContext = SQLContext(sc)
        >>> tup = [(1, "a"), (1, "a"), (2, "a"), (1, "b"), (2, "b"), (3, "b")]
        >>> df = sqlContext.createDataFrame(tup, ["id", "category"])
        >>> window = Window.partitionBy("category").orderBy("id").rangeBetween(Window.currentRow, 1)
        >>> df.withColumn("sum", func.sum("id").over(window)).sort("id", "category").show()
        +---+--------+---+
        | id|category|sum|
        +---+--------+---+
        |  1|       a|  4|
        |  1|       a|  4|
        |  1|       b|  3|
        |  2|       a|  2|
        |  2|       b|  5|
        |  3|       b|  3|
        +---+--------+---+

        """
        if start <= Window._PRECEDING_THRESHOLD:
            start = Window.unboundedPreceding
        if end >= Window._FOLLOWING_THRESHOLD:
            end = Window.unboundedFollowing
        sc = SparkContext._active_spark_context  # type: ignore[attr-defined]
        jspec = sc._jvm.org.apache.spark.sql.expressions.Window.rangeBetween(start, end)
        return WindowSpec(jspec)


class WindowSpec(object):
    """
    A window specification that defines the partitioning, ordering,
    and frame boundaries.

    Use the static methods in :class:`Window` to create a :class:`WindowSpec`.

    .. versionadded:: 1.4.0
    """

    def __init__(self, jspec: JavaObject) -> None:
        self._jspec = jspec

    def partitionBy(self, *cols: Union["ColumnOrName", List["ColumnOrName"]]) -> "WindowSpec":
        """
        Defines the partitioning columns in a :class:`WindowSpec`.

        .. versionadded:: 1.4.0

        Parameters
        ----------
        cols : str, :class:`Column` or list
            names of columns or expressions
        """
        return WindowSpec(self._jspec.partitionBy(_to_java_cols(cols)))

    def orderBy(self, *cols: Union["ColumnOrName", List["ColumnOrName"]]) -> "WindowSpec":
        """
        Defines the ordering columns in a :class:`WindowSpec`.

        .. versionadded:: 1.4.0

        Parameters
        ----------
        cols : str, :class:`Column` or list
            names of columns or expressions
        """
        return WindowSpec(self._jspec.orderBy(_to_java_cols(cols)))

    def rowsBetween(self, start: int, end: int) -> "WindowSpec":
        """
        Defines the frame boundaries, from `start` (inclusive) to `end` (inclusive).

        Both `start` and `end` are relative positions from the current row.
        For example, "0" means "current row", while "-1" means the row before
        the current row, and "5" means the fifth row after the current row.

        We recommend users use ``Window.unboundedPreceding``, ``Window.unboundedFollowing``,
        and ``Window.currentRow`` to specify special boundary values, rather than using integral
        values directly.

        .. versionadded:: 1.4.0

        Parameters
        ----------
        start : int
            boundary start, inclusive.
            The frame is unbounded if this is ``Window.unboundedPreceding``, or
            any value less than or equal to max(-sys.maxsize, -9223372036854775808).
        end : int
            boundary end, inclusive.
            The frame is unbounded if this is ``Window.unboundedFollowing``, or
            any value greater than or equal to min(sys.maxsize, 9223372036854775807).
        """
        if start <= Window._PRECEDING_THRESHOLD:
            start = Window.unboundedPreceding
        if end >= Window._FOLLOWING_THRESHOLD:
            end = Window.unboundedFollowing
        return WindowSpec(self._jspec.rowsBetween(start, end))

    def rangeBetween(self, start: int, end: int) -> "WindowSpec":
        """
        Defines the frame boundaries, from `start` (inclusive) to `end` (inclusive).

        Both `start` and `end` are relative from the current row. For example,
        "0" means "current row", while "-1" means one off before the current row,
        and "5" means the five off after the current row.

        We recommend users use ``Window.unboundedPreceding``, ``Window.unboundedFollowing``,
        and ``Window.currentRow`` to specify special boundary values, rather than using integral
        values directly.

        .. versionadded:: 1.4.0

        Parameters
        ----------
        start : int
            boundary start, inclusive.
            The frame is unbounded if this is ``Window.unboundedPreceding``, or
            any value less than or equal to max(-sys.maxsize, -9223372036854775808).
        end : int
            boundary end, inclusive.
            The frame is unbounded if this is ``Window.unboundedFollowing``, or
            any value greater than or equal to min(sys.maxsize, 9223372036854775807).
        """
        if start <= Window._PRECEDING_THRESHOLD:
            start = Window.unboundedPreceding
        if end >= Window._FOLLOWING_THRESHOLD:
            end = Window.unboundedFollowing
        return WindowSpec(self._jspec.rangeBetween(start, end))


def _test() -> None:
    import doctest
    import pyspark.sql.window
    SparkContext('local[4]', 'PythonTest')
    globs = pyspark.sql.window.__dict__.copy()
    (failure_count, test_count) = doctest.testmod(
        pyspark.sql.window, globs=globs,
        optionflags=doctest.NORMALIZE_WHITESPACE)
    if failure_count:
        sys.exit(-1)


if __name__ == "__main__":
    _test()