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 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
and0
, which computes the rolling average from the current row back to the first row of the dataset.
 The default integer parameter values are
 This function works with the Window transform. See Window Transform.
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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
rowsAfter_integer
compute the rolling average function 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 value0
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.
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