IBM Cognos User Manual page 78

calculations are computed in Cognos Transformer and then added to the
PowerCube, the results immediately appear in the OLAP reporting component for
every measure specified in the cube.
For example, you can base a calculation on the special time categories Current
Month and Last Month. You use the percent-growth function to create a new
calculated category named Monthly Growth which shows the percentage change
between these two items for all measures included in your PowerCube.
Category calculation is based on a formula and a set of categories to which the
formula applies. You compose the formula with the help of an expression editor
and a selection list of functions and operators. You then specify the categories to
which the formula applies: either a single category, a category set (if supported for
that function), or all categories in the level. Sets are convenient category groupings
that may be from the same level, or from different levels.
You can view a category calculation by opening the Calculated Category property
sheet or by using the Show Category Calculation command on the Diagram
menu.
The formula varies according to the context of each category. The applicable
formula can only reference another single category, not a category set or a level.
Separately defined categories are useful when you want to create special
groupings, such as 'Japan'+'Hong Kong'. Calculated categories are identified in the
Categories diagram by their own icon
Creating a Calculated Category at the Dimension Level
When created at the dimension level, new calculated categories become siblings of
the categories from which they are derived.
You can create calculated categories at the dimension level by using the
Dimension property sheet, or individually at the child category level, by using the
Change to Calculated Category command on the Diagram menu.
Procedure
1. Open the property sheet for the dimension that is to contain the calculated
2. Click Add.
3. In the Label box, enter a name for your calculated category.
4. If you want all the calculated categories listed together in your OLAP reporting
5. Click Calculation.
6. In the left pane of the expression editor, expand the Functions folder, select the
7. Next, expand the Levels folder and select the appropriate level for the
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IBM Cognos Transformer Version 10.1.1: User Guide
category and click the Calculation tab.
component, select the Group calculated categories together check box.
mathematical function you want to use, and click the right-arrow button to
insert it into the Expression definition box in the right pane of the editor.
Tip: You can also double-click or click and drag the parameter to add it to the
calculation.
expression.
Tip: You can also select and drag the appropriate level from the Categories
diagrammer, or lower pane of the Categories diagram, directly into your