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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 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:

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Output: Generates the new column, which contains the rolling sum of the current row and the two three previous row values in the myNumber column.

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

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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 four five rows after before it are used in the computation. Negative values for k compute the rolling average from rows preceding the current one.

  • rowBefore=10 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.

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