Charts are an indispensable part of any data visualization work. People can grok visual representation of data easily than a textual variety. Today there are a huge number of free chart libraries available to display visualizations on websites. Below is a small list of some of the libraries available for displaying charts using php.
output format: Silverlight
license: GPL 3.0 / Commercial
Visifire is a set of open source data visualization components – powered by Microsofts Silverlight technology. Visifire can be used in both WPF & Silverlight applications. Using the same API, charts in both Silverlight & WPF environments can be created within minutes. Visifire is independent of server side technology. It can be used with ASP, ASP.Net, PHP, JSP, ColdFusion, Ruby on Rails or just simple HTML. The website also includes a chart designer for you yo play with. The components also support excellent animations.
2. FusionCharts – PHP Charts
Output Format:Interactive Chart / Image / PDF
License:Free / Commercial
FusionChartsSuite XT can also connect to dynamic sources of data using server side scripts like ASP, ASP.NET C#, ASP.NET VB.NET, PHP, J2EE, Ruby on Rails, ColdFusion etc.
PHP/SWF Charts is a simple, yet powerful PHP tool to create attractive web charts and graphs from dynamic data.
Use PHP scripts to generate or gather the data from databases, then pass it to this tool to generate Flash (swf) charts and graphs. Any other scripting language (ASP, CFML, Perl, etc.) can be used with XML/SWF Charts (the XML version of the same tool.)
pChart is a PHP class oriented framework designed to create visually appealing charts. Data can be retrieved from SQL queries, CSV files, or manually provided. This project is still under development and new features or fix are made every week.
One of my favorites. AmCharts is a toolbox of Flash charts for your websites. AmCharts can automatically extract data from simple CSV or XML files, or they can read dynamic data generated with PHP, .NET, Java, Ruby on Rails, Perl, ColdFusion, and many other programming languages.
Common amCharts features:
eZ components are an enterprise ready general purpose PHP components library by eZ systems. As a set of quality independent building blocks for PHP application development, eZ components help you speed up your php development.
The Graph component enables you to create line, pie and bar charts. The output driver mechanism allows you to create different image types from each chart, and the available renderers make the chart output customizable from simple two-dimensional charts to beautiful three-dimensional data projections.
Some recent additions include ChartLogix, a commercial PHP charting library that includes many commonly used data visualizations. The charting library is included in one self-contained PHP file, which makes it easier to use and embed in your applications.