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.
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.
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