png-example

Salt PNG Example

Shows a single day of New York taxi cab pickups

This example illustrates how to use Salt to generate PNG image output. Salt features used:

• Loading and using CSV data in Spark
• Count bin aggregator
• Min-max tile aggregator
• PNG image output format
• Saving results to local filesystem on Spark Master

Building the Example

To build the example you must first generate the PNG images 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 -