How to: Apply a Custom Calculation to a Data Field

• Sep 19, 2023
• 4 minutes to read

Summaries in the data area are calculated according to the data field’s PivotDataField.SummarizeValuesBy property. By default, they are displayed “as is”. However, you can use the PivotDataField.ShowValuesWithCalculation method overloads to apply an additional calculation option to the raw summary values to change the way they are displayed in the PivotTable report.

The available calculation options are defined by the values of the PivotShowValuesAsType enumeration and listed in the table below. Depending on the selected option, you may need to specify either a base field or a base field and its base item that will serve as a basis for a custom calculation. Only a field from the row or column area can be used as a base field, otherwise, all results will be shown as a #N/A error.

Calculation Option	PivotShowValuesAsType Member	Description
% of Grand Total	PivotShowValuesAsType.PercentOfTotal	Displays values as the percentage of the grand total of all values in the PivotTable report.
% of Column Total	PivotShowValuesAsType.PercentOfColumn	Displays values in each column as the percentage of the total value of the column.
% of Row Total	PivotShowValuesAsType.PercentOfRow	Displays values in each row as the percentage of the total value of the row.
% of Parent Column Total	PivotShowValuesAsType.PercentOfParentColumn	Displays values in each inner column as the percentage of the total of the parent item in the outer column.
% of Parent Row Total	PivotShowValuesAsType.PercentOfParentRow	Displays values in each inner row as the percentage of the total of the parent item in the outer row.
Index	PivotShowValuesAsType.Index	Calculates the relative importance of each summary value by using the following formula: ((value in cell) x (Grand Total of Grand Totals)) / ((Grand Row Total) x (Grand Column Total))
% of Parent Total	PivotShowValuesAsType.PercentOfParent	Displays values in a data field as the percentage of the value of the parent item in the specified base field.
Rank Smallest to Largest	PivotShowValuesAsType.RankAscending	Displays the rank of values for a specific base field, listing the smallest item in the field as 1, and each larger value with a higher rank value.
Rank Largest to Smallest	PivotShowValuesAsType.RankDescending	Displays the rank of values for a specific base field, listing the largest item in the field as 1, and each smaller value with a higher rank value.
Running Total In	PivotShowValuesAsType.RunningTotal	Displays values for successive items in the base field as a running total.
% Running Total In	PivotShowValuesAsType.PercentOfRunningTotal	Calculates a running total for successive items in the base field as a percentage of the grand total value.
% Of	PivotShowValuesAsType.Percent	Displays values as the percentage of the value of the base item in the base field.
Difference From	PivotShowValuesAsType.Difference	Displays values as the difference from the value of the base item in the base field.
% Difference From	PivotShowValuesAsType.PercentDifference	Displays values as the percentage difference of the value of the base item in the base field.

To remove any custom calculation applied to a data field, pass the PivotShowValuesAsType.NoCalculation enumeration member to the PivotDataField.ShowValuesWithCalculation method as a parameter, or call the PivotDataField.ShowValuesWithoutCalculation method.

The following example demonstrates how to calculate the difference in product sales between the current quarter and the previous quarter. Values in the data field are summarized using the “Sum” function.

View Example

ValueFieldSettingsActions.cs

Worksheet worksheet = workbook.Worksheets["Report14"];
workbook.Worksheets.ActiveWorksheet = worksheet;

// Access the pivot table by its name in the collection
PivotTable pivotTable = worksheet.PivotTables["PivotTable1"];

// Access the data field by its index in the collection.
PivotDataField dataField = pivotTable.DataFields[0];
// Display the difference in product sales between the current quarter and the previous quarter.
dataField.ShowValuesWithCalculation(PivotShowValuesAsType.Difference, pivotTable.Fields["Quarter"], PivotBaseItemType.Previous);

ValueFieldSettingsActions.vb

Dim worksheet As Worksheet = workbook.Worksheets("Report14")
workbook.Worksheets.ActiveWorksheet = worksheet

' Access the pivot table by its name in the collection
Dim pivotTable As PivotTable = worksheet.PivotTables("PivotTable1")

' Access the data field by its index in the collection.
Dim dataField As PivotDataField = pivotTable.DataFields(0)
' Display the difference in product sales between the current quarter and the previous quarter.
dataField.ShowValuesWithCalculation(PivotShowValuesAsType.Difference, pivotTable.Fields("Quarter"), PivotBaseItemType.Previous)

The image below shows the result.