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ROLLINGMODE Function

Computes the rolling mode (most common value) forward or backward of the current row within the specified column. Input values can be Integer, Decimal, or Datetime data type.

  • 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.

Wrangle vs. SQL: This function is part of Wrangle, a proprietary data transformation language. Wrangle is not SQL. For more information, see Wrangle Language.

Basic Usage

Column example:

rollingmode(myCol)

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

Rows before example:

rollingmode(myNumber, 3)

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

Rows before and after example:

rollingmode(myNumber, 3, 2)

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.

Syntax and Arguments

rollingmode(col_ref, rowsBefore_integer, rowsAfter_integer) order: order_col [group: group_col]

Argument

Required?

Data Type

Description

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

For more information on the order and group parameters, see Window Transform.

For more information on syntax standards, see Language Documentation Syntax Notes.

col_ref

Name of the column whose values are used to compute the function.

注記

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

Multiple columns and wildcards are not supported.

Usage Notes:

Required?

Data Type

Example Value

Yes

String (column reference to Integer or Decimal values)

myColumn

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.

Usage Notes:

Required?

Data Type

Example Value

No

Integer

4

Examples

ヒント

For additional examples, see Common Tasks.

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:

Turn

Result

1

heads

2

heads

3

tails

4

heads

5

heads

6

tails

7

tails

8

heads

9

tails

10

heads

11

tails

12

heads

13

tails

14

heads

15

heads

16

tails

17

tails

18

tails

19

heads

20

heads

Transformation:

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

Transformation Name

Edit column with formula

Parameter: Columns

Result

Parameter: Formula

if(Result == 'heads', 0, 1)

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

Transformation Name

New formula

Parameter: Formula type

Multiple row formula

Parameter: Formula

rollingmode(Result, 4, 0)

Parameter: Sort rows by

Turn

Parameter: New column name

'mostCommonLast5'

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

Transformation Name

Edit column with formula

Parameter: Columns

mostCommonLast5

Parameter: Formula

if(mostCommonLast5 == 0, 'heads-last5', 'tails-last5')

Results:

Turn

Result

mostCommonLast5

1

heads

heads-last5

2

heads

heads-last5

3

tails

heads-last5

4

heads

heads-last5

5

heads

heads-last5

6

tails

heads-last5

7

tails

tails-last5

8

heads

heads-last5

9

tails

tails-last5

10

heads

tails-last5

11

tails

tails-last5

12

heads

heads-last5

13

tails

tails-last5

14

heads

heads-last5

15

heads

heads-last5

16

tails

heads-last5

17

tails

tails-last5

18

tails

tails-last5

19

heads

tails-last5

20

heads

tails-last5