In my initial coverage of the Google Prediction API, I was very curious why Google would be so magnanimous as to open up this API for public use. This is a plausible answer from Google:
We do not describe the actual logic of the Prediction API in these documents, because that system is constantly being changed and improved. Therefore we can’t provide optimization tips that depend on specific implementations of our matching logic, which can change without notice.
An older version of a prediction API
Based on some of the user comments in the Google group for the Prediction API, I would guess that it is one of the more difficult of all Google APIs to understand and use. Similarly, it will probably be challenging to get meaningful results.
Google advises that all the following are prerequisite for using the Prediction API:
- an active Google Storage account
- an APIs Console project with both the Google Prediction API and the Google Storage for Developers API activated
And of course, a Google account! See getting started for further details.
Free but not forever
Nor is the Prediction API free of charge indefinitely. According to the initial terms, usage is free for all users for the first six months, up to the following limits per project:
- Predictions: 100 predictions/day
- Hosted model predictions: Hosted models have a usage limit of 100 predictions/day/user across all models
- Training: 5 MB trained/day
- Streaming updates: 100 streaming updates/day
- Lifetime cap: 20,000 predictions
This free quota expires at the end of the six month introductory period. The introductory periods begins the day that Google Prediction is activated for a project in the Google APIs console. Remember that charges associated with Google Storage must be included to figure total cost!
Presumably this is an API that Google won’t be deprecating without replacement any time soon. However, there is a separate Terms of Service for the Prediction API, which does give Google the right to do exactly that. I think that is standard language though, as Google is not contractually bound to support a free, or even paid but unprofitable service unless explicitly specifically stated.
Conclusion about the Prediction API
A great deal more information is available from the Prediction API developer guide including an example application for movie recommendations.
The Google Prediction API is probably best used as a sandbox. It may be helpful for deciding whether one wants to use machine learning for predictive purposes. If one decides to go ahead with this approach, there are probably more suitable alternatives than the Google Prediction API for an application intended for production use.