ParallelPeriod()

Some node navigation methods are especially suited for hierarchies containing periodic data, first and foremost time hierarchies. Time is structured hierarchically by nature (like year, quarter, month), and the time periods are recurrent. Because the nodes in a time hierarchy are obvious, any nodes that miss data can be detected automatically. One of these navigation methods is ParallelPeriod(), which references the corresponding node in the previous branch of the hierarchy within the same level of the hierarchy. When you use this method in an expression, and any nodes are missing data, the expression will return empty values for such nodes.

The ParallelPeriod() method is exemplified below.

This method combines a set of node navigation methods into one method. For example, using Q3, 2019 as the current node, the method navigates up one level in the hierarchy, then navigates to this level's previous node, and then down one level to the node that matches the starting point.

Note: You cannot use the method in a time hierarchy with three levels, years, quarters, and months. This is because the method would not find a matching node. For example, if the starting point is April in Q2 2019, the method navigates from April up to the parent Q2, then back to Q1, but will not find any April there when navigating down.

Example

Note: The expression in the example assumes that in-memory data is used.

The bar chart shows quarterly sales during 2015-2017.

Assume you want to compare the sales in a particular quarter with the sales in the same quarter the previous year, for example, compare sales in Q3 2017 with sales in Q3 2016. Apply the following expression (which calculates the difference in sales in absolute figures):

We can now see that, for example, the sales amount in Q3 2017 exceeded the sales in Q3 2016 by 148783 (359800-211017). In addition, now it becomes easier to identify quarters with sales going down compared to the sales one year ago, as these bars get negative values.

Tip: The part furthest to the left is empty, because there are no previous nodes to make a comparison with. If you want to hide this part, add a zoom slider and drag the slider to a suitable position as shown below.