applying where after group by in dataset

[subash basnet]

Hello all,

In the following dataset:
DataSet<Tuple2<Point, Boolean>> distancePoints;

I wanted to count the number of *distancePoints* where boolean value is
either true of false.

distancePoints.groupBy(1).........

didn't find how to apply there 'where' clause here.

Best Regards,
Subash Basnet