This is a demo project that shows how to create a project using LensKit and set get the recommender running. It creates a simple command line application that builds a recommender from a delimited text file of ratings, then recommends items for users specified at the command line.
The main code is in org.grouplens.lenskit.hello.HelloLenskit. There are comments
so you can follow along and see what each stage of the process does.
If you are building a web application, you will need to adapt this project. But the basic things done in that class will need to be done in your application somewhere.
The LensKit home page has further documentation for LensKit, as well as links to our bug tracker and wiki. Also be sure to subscribe to our mailing list and ask any further questions you may have about using LensKit, and follow our Twitter account for updates on new releases and developments.
This project uses Gradle for build and dependency management. It is
easy to import into an IDE; Gradle support is included with or available for
NetBeans, IntelliJ IDEA, and Eclipse. These IDEs will import your project directly
from the Gradle build.gradle file and set up the build and dependencies.
The build.gradle file contains the project definition and its dependencies. Review
this for how we pull in LensKit, and how to depend on other modules.
In the Gradle build, we use the Application plugin to create a shell script and copy the dependency JARs in order to run the LensKit application.
LensKit Hello runs on a copy of the MovieLens Latest Small data set, included in the data directory.
More up-to-date versions of this data set, along with a larger data set of 20M ratings, can be downloaded
from http://grouplens.org/datasets/movielens/.
You can run lenskit-hello through your IDE, or from the command line as follows:
$ ./gradlew build
$ /bin/sh build/install/lenskit-hello/bin/lenskit-hello <userid>
If you are on Windows, do:
C:\LensKit\lenskit-hello> .\gradlew.bat build
C:\LensKit\lenskit-hello> .\build\install\lenskit-hello\bin\lenskit-hello.bat <userid>
A user ID of 72 is valid and good for a quick demo. You can specify more than one user ID, and it will produce recommendations for each user.
Have fun!
Various people have ported the lenskit-hello project to other languages: