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Comment: Published by Scroll Versions from space DEV and version r0811

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Excerpt

Computes the rolling unique kth largest value forward or backward of the current row. Inputs can be Integer, Decimal, or Datetime.

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 1099, 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 Window transform. See Window Transform.

For more information on a non-rolling version of this function, see KTHLARGESTUNIQUE Function.

D s lang vs sql

D s
snippetBasic

Column example:

D lang syntax
RawWrangletrue
Typeref
showNotetrue
WrangleTextderive type:single value:rollingkthlargestunique(myCol, 2)

rollingkthlargestunique(myCol, 2)

Output: Returns the rolling second largest unique value in the myCol column from the first row of the dataset to the current one.

Rows before example:

D lang syntax
RawWrangletrue
Typeref
showNotetrue
WrangleTextwindow value:rollingkthlargestunique(myNumber, 2, 3)

rollingkthlargestunique(myNumber, 2, 3)

Output: Returns 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:

D lang syntax
RawWrangletrue
Typeref
showNotetrue
WrangleTextwindow value:rollingkthlargestunique(myNumber, 4, 3, 2)

rollingkthlargestunique(myNumber, 4, 3, 2)

Output: Returns 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.     

D s
snippetSyntax

D lang syntax
RawWrangletrue
Typesyntax
showNotetrue
WrangleTextwindow value:rollingkthlargestunique(col_ref, rowsBefore_integer, rowsAfter_integer) order: order_col [group: group_col]

rollingkthlargestunique(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
k_integerYinteger (positive)The ranking of the unique value to extract from the source column
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.

D s lang notes

col_ref

Name of the column whose values are used to compute the function. Inputs must be Integer, Decimal, or Datetime values.

Info

NOTE: If the input is in Datetime type, the output is in unixtime format. You can wrap these outputs in the DATEFORMAT function to output the results in the appropriate Datetime format. See DATEFORMAT Function.

  • Multiple columns and wildcards are not supported.

D s
snippetusage

Required?Data TypeExample Value
YesString (column reference)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.

Info

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.

D s
snippetusage
 

Required?
Data Type
Example Value
YesInteger (positive)4

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 rowsAfter_integer compute the rolling function 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.

D s
snippetusage

Required?Data TypeExample Value
NoInteger4

D s
snippetExamples

Example - ROLLINGKTHLARGEST functions

Include Page
EXAMPLE - ROLLINGKTHLARGEST Functions
EXAMPLE - ROLLINGKTHLARGEST Functions

D s also
labelwindow