If you haven’t already done so, you’ll need to first setup your Flink development environment. See How to do the Exercises for an overall introduction to these exercises.

The task of the “Taxi Ride Cleansing” exercise is to cleanse a stream of TaxiRide events by removing events that do not start or end in New York City.

The GeoUtils utility class provides a static method isInNYC(float lon, float lat) to check if a location is within the NYC area.

Input Data

This series of exercises is based a stream of taxi ride events. The Taxi Data Stream instructions show how to setup the TaxiRideSource which generates a stream of TaxiRide events.

Expected Output

The result of the exercise should be a DataStream<TaxiRide> that only contains events of taxi rides which both start and end in the New York City area as defined by GeoUtils.isInNYC().

The resulting stream should be printed to standard out.

Getting Started

Rather than following the links in this section, you'll do better to find these classes in the flink-training-exercises project in your IDE.

Exercise Classes

This exercise uses these classes:

Tests

You will find the test for this exercise in

com.dataartisans.flinktraining.exercises.datastream_java.basics.RideCleansingTest

Like many of the other exercises, at some point this class throws an exception

    throw new MissingSolutionException();

Once you remove this line the test will fail until you provide a working solution. You might want to first try something clearly broken, such as

return false;

in order to verify that the test does indeed fail when you make a mistake, and then work on implementing a proper solution.

Implementation Hints

Flink’s DataStream API features a DataStream.filter(FilterFunction) transformation to filter events from a data stream. The GeoUtils.isInNYC() function can be called within a FilterFunction to check if a location is in the New York City area. Your filter function should check both the starting and ending locations of each ride.

Documentation

Reference Solutions

Reference solutions are available at GitHub and in the training exercises project: