 guarantee that the dataset has unique tuples of [simulation, placement, year-month]
Map initAgg = Reductions.groupByColumnsAgg(dsSeq, vector(&quot;simulation&quot;, &quot;placement&quot;, &quot;year-month&quot;),
                                               hashmap(&quot;count&quot;, Reductions.sum(&quot;count&quot;)),
                                               null);
println(head(initAgg));
//[&quot;simulation&quot; &quot;placement&quot; &quot;year-month&quot;]-aggregation [5 4]:

//| simulation | p