• 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 mode 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.

• 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 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 MODE Function.

Column example:

Output: Returns the rolling mode of all values in the myCol column.

Rows before example:

Output: Returns the rolling mode of the current row and the three previous row values in the myNumber column.

Rows before and after example:

Output: Returns the rolling mode of the three previous row values, the current row value, and the two rows after the current one in the myNumber column.     

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.

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 five rows before it are used in the computation. Negative values for rowsAfter_integer compute the rolling 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 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.

Example - Counting most common coin flips

In the following table, 20 coin flips are tabulated. You want to capture a rolling evaluation of the most common value.

Source:

Transformation:

To use the ROLLINGMODE function, the results need to be converted to numeric values:

Now calculate the ROLLINGMODE for the preceding five values for each row:

You can now convert the binary values back to text information:

Results: