Reducing dimensions by Reductions or Rollups

Often you will wish to work with only a summarized form of a dimension. That is done by “collapsing” or “rolling up” an axis towards the centre of the Ravel.

Click on the axis you wish to roll-up, and drag its arrowhead towards the centre of the Ravel. This collapses the axis and aggregates the data according to the current setting of “Set Next Aggregation” on the right-click context menu. Six forms of aggregation are supported: Sum, Product, Average, Standard Deviation, Minimum and Maximum. Once you have selected one of these operations, it will be applied to the next axis that is rolled up.

Figure 25 shows the “Set next aggregation” menu, and Figure 26 shows a roll-up performed on the Reference Area axis, where the aggregation method chosen is the average, “Pick Slices” has also been used to select just European countries.

A limited range of dates have been chosen using a caliper—using the context-menu choice “Toggle axis calipers”. The caliper has been applied to the Date axis to select all months from

1950 till the latest data in 2024 (later versions of Ravel will support multiple calipers on an axis, to enable non-contiguous data ranges to be selected when desired).

Figure 25: Setting the next aggregation command on a roll-up

for the last 75 years.

Figure 26: The right-click/context menu for setting the next aggregation method.

Figure 27: Collapsing ("Rolling Up") a Ravel dimension to summarise data

You can do a lot to analyse data just by exploiting the features of the Ravel, but the real power of Ravel the program comes when you combine Ravels for data selection with flowchart formulas for analysis. This necessitates using named variables, and here Ravel is much more flexible than Spreadsheets or BI programs.