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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 standard deviation of previous values is undefined.
The row from which to extract a value is determined by the order in which the rows are organized based on the
orderparameter.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
-1and0, which computes the rolling function from the current row back to the first row of the dataset.
- The default integer parameter values are
- This function works with the following transforms:Window transform. See Window Transform
- Set Transform Derive Transform.
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For more information on a non-rolling version of this function, see STDEV Function.
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Column example:
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| ROLLINGSTDEV
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rollingstdev(myCol) |
Output:
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Returns the rolling standard deviation of all values in the myCol column
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Rows before example:
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rollingstdev(myNumber, 100) |
Output:
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Returns the rolling standard deviation of the current row and the 100 previous row values in the myNumber column.
Rows before and after example:
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rollingstdev(myNumber, 3, 2) |
Output:
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Returns the rolling standard deviation of the
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three previous row values, the current row value, and the two rows after the current one in the myNumber column.
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rollingstdev(col_ref, rowsBefore_integer, rowsAfter_integer) order: order_col [group: group_col] |
| Argument | Required? | Data Type | Description |
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| col_ref | Y | string | Name of column whose values are applied to the function |
| rowsBefore_integer | N | integer | Number of rows before the current one to include in the computation |
| rowsAfter_integer | N | integer | Number of rows after the current one to include in the computation |
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Integers representing the number of rows before or after the current one from which to compute the rolling function, including the current row. For example, if the first value is 5, the current row and the four rows five before after it are used in the computation. Negative Negative values for krowsAfter_integer compute the rolling average function from rows preceding the current one.
rowBefore=10generates the current row value only.rowBefore=-1uses all rows preceding the current one.- If
rowsAfteris not specified, then the value0is applied. - If a
groupparameter is applied, then these parameter values should be no more than the maximum number of rows in the groups.
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