View source for How to combine multiple calculations into a single result


{{howto|title=
|Hover over [[Overlay]]s in the [[ribbon bar]].
|Hover over Grid Calculation under Add New, and select [[Combo Overlay|Combo]].
|For Grid A, select a Grid Overlay
|For Formula, write AT if you want to collect all timeframes, A if you only want to collect the last timeframe.
|Click on the update link to initialize the Combo Overlay
|Select the Attributes tab
|In the Add new Attribute name field, write '''SKIP_NO_DATA'''
|In the Add new Attribute value field, write '''1'''
|Click on the Save new Attribute button.
|Hover over the [[Calculation Cloud]] in the ribbon bar.
|Select the option Reset Excel X-Queries.
|The Combo Overlay is now setup to accumulate overlay results.
}}


<gallery>
File:accumulation_combo_general.jpg|General setup for accumulating all timeframes of a Grid Overlay.
File:accumulation_combo_skip_nodata.jpg|Adding the attribute named '''SKIP_NO_DATA'''.
File:accumulation_combo_reset_x_queries.jpg| Reset Excel X-Queries under [[Calculation Cloud]].
</gallery>

== Example Demo Rainfall ==
{{howto|title=
|Open the project Demo Rainfall.
|Select Areas in the ribbon bar.
|Select the group named '''WATERLEVEL''' and click on the deactivate button to deactivate the areas.
|Follow the How-to above for the Accumulation Combo Overlay.
|Inspect the initial Combo Overlay, it should be empty.
|Select Areas in the ribbon bar.
|Activate the first three Water Level Areas. 
|Notice both the Combo Overlay and Rainfall Overlay calculated only for those areas.
|Deactivate the areas again, and activate the remaining Water Level Areas. 
| Notice the Combo Overlay is calculated for all areas, while the Rainfall overlay is only calculated for the last 5 Water Level Areas.
|Select the ''Polder Kockengen'' Area.
|Select the Attribute tab and add new attribute: '''WATERLEVEL''' with a value of -3.
|Notice that the ''Polder Kockengen'' Area is now calculated as well in the Combo Overlay, while the Rainfall Overlay is only calculated for the ''Polder Kockengen'' Area.
}}