There are lots of solutions out there when it comes to graphing data with PHP, mostly surrounding the GD graphics library that's included with most of the recent PHP distributions. Included in this list is the PEAR package Image_Graph, and PHPBuilder.com has created this introduction to help get you started with it.
This article looks at PEAR's Image_Graph package, which is released under the Lesser GPL. It's a package that has very little documentation, but which deserves more recognition. It's helpful to have used PEAR before, but if this is the first PEAR package you'll use, you'll probably cope just fine.
Formerly a SourceForge package known as GraPHPite, it merged with and took the name of an older PEAR Image_Graph package. The graphs, charts and plots produced by Image_Graph are highly customizable, and can be any of area, band, bar, box and whisker, candlestick, impulse, map, line, pie, radar, scatter, smoothed line and step.
There's a brief installation section to get things all set up, followed by a simple bar chart example that serves as a base for the rest of the code. They enhance it with colors (manually and via arrays), changing the font settings, changing out the type of graph rendered, and adding a heading to better define the graph's contents.