# ROLLINGSUM Function

Computes the rolling sum of values forward or backward of the current row within the specified column.
• If an input value is missing or null, it is not factored in the computation. For example, for the first row in the dataset, the rolling sum of previous values is the value in the first row.
• The row from which to extract a value is determined by the order in which the rows are organized based on the order parameter.

• If you are working on a randomly generated sample of your dataset, the values that you see for this function might not correspond to the values that are generated on the full dataset during job execution.

• The function takes a column name and two optional integer parameters that determine the window backward and forward of the current row.
• The default integer parameter values are -1 and 0, which computes the rolling average from the current row back to the first row of the dataset.
• This function works with the following transforms:

## Basic Usage

Column example:

rollingsum(myCol)

Output: Returns the rolling sum of all values in the myCol column.

Rows before example:

rollingsum(myNumber, 3)

Output: Returns the rolling sum of the current row and the three previous row values in the myNumber column.

Rows before and after example:

rollingsum(myNumber, 3, 2)

Output: Returns the rolling sum of the three previous row values, the current row value, and the two rows after the current one in the myNumber column.

## Syntax

rollingsum(col_ref, rowsBefore_integer, rowsAfter_integer) order: order_col [group: group_col]

ArgumentRequired?Data TypeDescription
col_refYstringName of column whose values are applied to the function
rowsBefore_integerNintegerNumber of rows before the current one to include in the computation.
rowsAfter_integerNintegerNumber of rows after the current one to include in the computation

For more information on the order and group parameters, see Window Transform.

### col_ref

Name of the column whose values are used to compute the rolling sum.

• Multiple columns and wildcards are not supported.

Usage Notes:

Required?Data TypeExample Value
YesString (column reference to Integer or Decimal values)myColumn

### rowsBefore_integer, rowsAfter_integer

Integers representing the number of rows before or after the current one from which to compute the rolling sum, including the current row. For example, if the first value is 5, the current row and the five rows before it are used in the computation. Negative values for k compute the rolling average from rows preceding the current one.

• rowBefore=0 generates the current row value only.
• rowBefore=-1 uses all rows preceding the current one.
• If rowsAfter is not specified, then the value 0 is applied.
• If a group parameter is applied, then these parameter values should be no more than the maximum number of rows in the groups.

Usage Notes:

Required?Data TypeExample Value
NoInteger4

## Examples

### Example - Rolling window functions

This example describes how to use the rolling computational functions:

• ROLLINGSUM - computes a rolling sum from a window of rows before and after the current row. See ROLLINGSUM Function.
• ROLLINGAVERAGE - computes a rolling average from a window of rows before and after the current row. See ROLLINGAVERAGE Function.
• ROWNUMBER - computes the row number for each row, as determined by the ordering column. See ROWNUMBER Function.

The following dataset contains sales data over the final quarter of the year.

Source:

DateSales
10/2/16200
10/9/16500
10/16/16350
10/23/16400
10/30/16190
11/6/16550
11/13/16610
11/20/16480
11/27/16660
12/4/16690
12/11/16810
12/18/16950
12/25/161020
1/1/17680

Transformation:

First, you want to maintain the row information as a separate column. Since data is ordered already by the Date column, you can use the following:

Transformation Name Window ROWNUMBER() Date

Rename this column to rowId for week of quarter.

Now, you want to extract month and week information from the Date values. Deriving the month value:

Transformation Name New formula Single row formula MONTH(Date) 'Month'

Deriving the quarter value:

Transformation Name New formula Single row formula (1 + FLOOR(((month-1)/3))) 'QTR'

Deriving the week-of-quarter value:

Transformation Name Window ROWNUMBER() QTR Date

Rename this column WOQ (week of quarter).

Deriving the week-of-month value:

Transformation Name Window ROWNUMBER() Month Date

Rename this column WOM (week of month).

Now, you perform your rolling computations. Compute the running total of sales using the following:

Transformation Name Window ROLLINGSUM(Sales, -1, 0) QTR Date

The -1 parameter is used in the above computation to gather the rolling sum of all rows of data from the current one to the first one. Note that the use of the QTR column for grouping, which moves the value for the 01/01/2017 into its own computational bucket. This may or may not be preferred.

Rename this column QTD (quarter to-date). Now, generate a similar column to compute the rolling average of weekly sales for the quarter:

Transformation Name Window ROUND(ROLLINGAVERAGE(Sales, -1, 0)) QTR Date

Since the ROLLINGAVERAGE function can compute fractional values, it is wrapped in the ROUND function for neatness. Rename this column avgWeekByQuarter.

Results:

When the unnecessary columns are dropped and some reordering is applied, your dataset should look like the following:

DateWOQSalesQTDavgWeekByQuarter
10/2/161200200200
10/9/162500700350
10/16/1633501050350
10/23/1644001450363
10/30/1651901640328
11/6/1665502190365
11/13/1676102800400
11/20/1684803280410
11/27/1696603940438
12/4/16106904630463
12/11/16118105440495
12/18/16129506390533
12/25/161310207410570
1/1/171680680680