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Computes the rolling unique kth largest value forward or backward of the current row. |
For purposes of this calculation, two instances of the same value are treated at one value for k. So, if your dataset contains four rows with column values 10, 9, 9, and 8, then KTHLARGESTUNIQUE returns 9 for k=2 and 8 for k=3.
ROLLINGKTHLARGESTUNIQUE computes the KTHLARGESTUNIQUE value across a defined window of values within a 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 calculation 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 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.
- Inputs:
- Required column name
- Required kth value, which is a positive integer
- 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 function from the current row back to the first row of the dataset.
- This function works with the following transforms:
For more information on a non-rolling version of this function, see KTHLARGESTUNIQUE Function.
Column example:
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derive type:single value:ROLLINGKTHLARGESTUNIQUE(myCol, 2) |
Output: Generates a new column containing the rolling second largest unique value in the
myCol column from the first row of the dataset to the current one.
Rows before example:
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window value:ROLLINGKTHLARGESTUNIQUE(myNumber, 2, 3) |
Output: Generates the new column, which contains the rolling second largest unique value of the current row and the two previous row values in the myNumber column.
Rows before and after example:
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window value:value:ROLLINGKTHLARGESTUNIQUE(myNumber, 4, 3, 2) |
Output: Generates the new column, which contains the rolling fourth largest unique value of the two previous row values, the current row value, and the two rows after the current one in the myNumber column.
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window value:value:ROLLINGKTHLARGESTUNIQUE(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 |
| k_integer | Y | integer (positive) | The ranking of the unique value to extract from the source column |
| 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 |
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 function.
- Multiple columns and wildcards are not supported.
| Required? | Data Type | Example Value |
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| Yes | String (column reference to Integer or Decimal values) | myColumn |
k_integer
Integer representing the ranking of the unique value to extract from the source column. Duplicate values are treated as a single value for purposes of this function's calculation.
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NOTE: The value for k must be an integer between 1 and 1,000 inclusive. |
k=1 represents the maximum value in the column. - If k is greater than or equal to the number of values in the column, the minimum value is returned.
- Missing and null values are not factored into the ranking of
k.
rowsBefore_integer, rowsAfter_integer
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 after it are used in the computation. Negative values for k compute the rolling average from rows preceding the current one.
rowBefore=1 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.
| Required? | Data Type | Example Value |
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| No | Integer | 4 |
Example - ROLLINGKTHLARGEST functions
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| EXAMPLE - ROLLINGKTHLARGEST Functions |
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| EXAMPLE - ROLLINGKTHLARGEST Functions |
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