org.apache.spark.sql.expressions

Class Window

Object

org.apache.spark.sql.expressions.Window

public class Window
extends Object

Utility functions for defining window in DataFrames.

   // PARTITION BY country ORDER BY date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW
   Window.partitionBy("country").orderBy("date").rowsBetween(Long.MinValue, 0)

   // PARTITION BY country ORDER BY date ROWS BETWEEN 3 PRECEDING AND 3 FOLLOWING
   Window.partitionBy("country").orderBy("date").rowsBetween(-3, 3)
 

Since:

1.4.0

Method Summary

Methods

Modifier and Type	Method and Description
static long	currentRow() Value representing the current row.
static WindowSpec	orderBy(Column... cols) Creates a WindowSpec with the ordering defined.
static WindowSpec	orderBy(scala.collection.Seq<Column> cols) Creates a WindowSpec with the ordering defined.
static WindowSpec	orderBy(String colName, scala.collection.Seq<String> colNames) Creates a WindowSpec with the ordering defined.
static WindowSpec	orderBy(String colName, String... colNames) Creates a WindowSpec with the ordering defined.
static WindowSpec	partitionBy(Column... cols) Creates a WindowSpec with the partitioning defined.
static WindowSpec	partitionBy(scala.collection.Seq<Column> cols) Creates a WindowSpec with the partitioning defined.
static WindowSpec	partitionBy(String colName, scala.collection.Seq<String> colNames) Creates a WindowSpec with the partitioning defined.
static WindowSpec	partitionBy(String colName, String... colNames) Creates a WindowSpec with the partitioning defined.
static WindowSpec	rangeBetween(long start, long end) Creates a WindowSpec with the frame boundaries defined, from start (inclusive) to end (inclusive).
static WindowSpec	rowsBetween(long start, long end) Creates a WindowSpec with the frame boundaries defined, from start (inclusive) to end (inclusive).
static long	unboundedFollowing() Value representing the last row in the partition, equivalent to "UNBOUNDED FOLLOWING" in SQL.
static long	unboundedPreceding() Value representing the last row in the partition, equivalent to "UNBOUNDED PRECEDING" in SQL.

Methods inherited from class Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

partitionBy

public static WindowSpec partitionBy(String colName,
                     String... colNames)

Creates a WindowSpec with the partitioning defined.

Parameters:

colName - (undocumented)

colNames - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

partitionBy

public static WindowSpec partitionBy(Column... cols)

Creates a WindowSpec with the partitioning defined.

Parameters:

cols - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

orderBy

public static WindowSpec orderBy(String colName,
                 String... colNames)

Creates a WindowSpec with the ordering defined.

Parameters:

colName - (undocumented)

colNames - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

orderBy

public static WindowSpec orderBy(Column... cols)

Creates a WindowSpec with the ordering defined.

Parameters:

cols - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

partitionBy

public static WindowSpec partitionBy(String colName,
                     scala.collection.Seq<String> colNames)

Creates a WindowSpec with the partitioning defined.

Parameters:

colName - (undocumented)

colNames - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

partitionBy

public static WindowSpec partitionBy(scala.collection.Seq<Column> cols)

Creates a WindowSpec with the partitioning defined.

Parameters:

cols - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

orderBy

public static WindowSpec orderBy(String colName,
                 scala.collection.Seq<String> colNames)

Creates a WindowSpec with the ordering defined.

Parameters:

colName - (undocumented)

colNames - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

orderBy

public static WindowSpec orderBy(scala.collection.Seq<Column> cols)

Creates a WindowSpec with the ordering defined.

Parameters:

cols - (undocumented)

Returns:

(undocumented)

Since:

1.4.0

unboundedPreceding

public static long unboundedPreceding()

Value representing the last row in the partition, equivalent to "UNBOUNDED PRECEDING" in SQL. This can be used to specify the frame boundaries:

   Window.rowsBetween(Window.unboundedPreceding, Window.currentRow)
 

Returns:

(undocumented)

Since:

2.1.0

unboundedFollowing

public static long unboundedFollowing()

Value representing the last row in the partition, equivalent to "UNBOUNDED FOLLOWING" in SQL. This can be used to specify the frame boundaries:

   Window.rowsBetween(Window.unboundedPreceding, Window.unboundedFollowing)
 

Returns:

(undocumented)

Since:

2.1.0

currentRow

public static long currentRow()

Value representing the current row. This can be used to specify the frame boundaries:

   Window.rowsBetween(Window.unboundedPreceding, Window.currentRow)
 

Returns:

(undocumented)

Since:

2.1.0

rowsBetween

public static WindowSpec rowsBetween(long start,
                     long end)

Creates a 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 6.

   import org.apache.spark.sql.expressions.Window
   val df = Seq((1, "a"), (1, "a"), (2, "a"), (1, "b"), (2, "b"), (3, "b"))
     .toDF("id", "category")
   df.withColumn("sum",
       sum('id) over Window.partitionBy('category).orderBy('id).rowsBetween(0,1))
     .show()

   +---+--------+---+
   | id|category|sum|
   +---+--------+---+
   |  1|       b|  3|
   |  2|       b|  5|
   |  3|       b|  3|
   |  1|       a|  2|
   |  1|       a|  3|
   |  2|       a|  2|
   +---+--------+---+
 

Parameters:

start - boundary start, inclusive. The frame is unbounded if this is the minimum long value (Window.unboundedPreceding).

end - boundary end, inclusive. The frame is unbounded if this is the maximum long value (Window.unboundedFollowing).

Returns:

(undocumented)

Since:

2.1.0

rangeBetween

public static WindowSpec rangeBetween(long start,
                      long end)

Creates a 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 0, because no value modification is needed, in this case multiple and non-numeric ORDER BY expression are allowed.

   import org.apache.spark.sql.expressions.Window
   val df = Seq((1, "a"), (1, "a"), (2, "a"), (1, "b"), (2, "b"), (3, "b"))
     .toDF("id", "category")
   df.withColumn("sum",
       sum('id) over Window.partitionBy('category).orderBy('id).rangeBetween(0,1))
     .show()

   +---+--------+---+
   | id|category|sum|
   +---+--------+---+
   |  1|       b|  3|
   |  2|       b|  5|
   |  3|       b|  3|
   |  1|       a|  4|
   |  1|       a|  4|
   |  2|       a|  2|
   +---+--------+---+
 

Parameters:

start - boundary start, inclusive. The frame is unbounded if this is the minimum long value (Window.unboundedPreceding).

end - boundary end, inclusive. The frame is unbounded if this is the maximum long value (Window.unboundedFollowing).

Returns:

(undocumented)

Since:

2.1.0