Visualization is a module for Drupal 7.x that provides a solid and easy accessible way to visualize data. It provides a theme hook that takes a data array and some options and will then render a chart in-place. It also provides a Views Display plugin so that users can easily visualize data retrieved through Views.
The different charting libraries are pluggable through the CTools Plugin system; the module provides an implementation for the Google Visualization API and Highcharts. Other modules will be able to add their own charting libraries by implementing an interface and making it known to CTools.
The code was originally part of a Google Summer of Code project whose purpose was to provide Reporting for Drupal Commerce; the result is the 3.x branch of the Commerce Reporting module. It was quickly decided to write the charting logic as generic as possible, so that it could potentially be spinned-off. The HEAD of the 7.x-3.x branch of Commerce Reporting already depends on Visualization, the alpha4 version still contains all the code itself.
- Data Visualization API uses an entity approach where each chart is unique entity.
- Google chart API is similar to the Visualization API, but only offers support for the deprecated Google Chart API.
- Charts and Graphs is also a similar project for Drupal 6; there seems to be little progress on a Drupal 7 version.