torque-example

Salt Torque Example

Shows a single day of New York taxi cab pickups animated over the course of the day

This example illustrates how to use Salt to generate TileJSON output compatible with CartoDB's Torque library. Salt features used:

• Loading and using CSV data in Spark
• Custom, non-trivial bin aggregator
• Compound tiling jobs (generates pickup and dropoff layers concurrently)
• Custom output format serialization
• Saving results to local filesystem on Spark Master

Building the Example

To build the example you must first generate the TileJSON data (written to the output/ directory) and then run the web app to view the results.

Tile Generation

First, we need to generate the tiles with the following commands:

cd generation/
./gradlew
./gradlew clean cleanGenEnv # clean up build environment
cd -

Viewing Results

Results are viewed through a simple web app contained in webapp/. After generating tiles, run:

cd webapp
npm install
npm start
cd -

The application will be available at http://localhost:3000/

Cleanup

You can remove the generated data by running:

cd generation/
./gradlew cleanOutput
cd -