Graphist Overview
Graphist presents plots of data as GIF, JPEG, or PNG images. Though PHP is used by Graphist to produce the image, pages that use its images can be ordinary HTML.
These images are added to a web page the same way as any image, such as a corporate logo or picture of your dog: an IMG tag. The tag's src parameter points to the Graphist PHP script installed on your server and includes the data to be plotted plus any desired formatting options. The graph is produced at the time the web page is viewed.
Features
Graphist can produce line graphs and bar charts. Many properties of the graph, including background, text, line, and bar colors can be specified. Explanation of use is found on the Samples and User Guide pages. The graphs on this site are unretouched results from Graphist (though they are static archived images).
Future Features
Enhancement requests can be seen and added on Graphist's SourceForge.net Feature Tracker page.
System Requirements
The Graphist software must be installed on a server with PHP version 4.3.0 or higher, with the GD library enabled. Users of Graphist need access to an installation of it but their pages do not need PHP.
Licensure
Graphist is offered according to the GNU General Public License (GPL) version 2.
The GPL is the definitive description of the license but in short it may be fair to say that Graphist is offered free of charge and nearly free of conditions on using, copying, distributing, and changing it. The author believes it works swell and that it can be useful but the author could be wrong. All of the results and implications of Graphist's use are the responsibility of its users, not of anyone else.
Issues and Limitations
Version 1 can only plot numeric data. Categorical data is on the list for a future version. Clever users can represent categorical data as numbers.
Grid line values are rounded to one decimal position of precision to avoid pollution of the plot space. Data that varies by less than that over the entire plotted space will have duplicate grid line values. For instance, a range of values from 1.001 to 1.004 will result in grid line labels of 1.0. Still, the data will be accurately plotted.
Image creation via PHP can be a resource intensive activity. The number of data points is limited by your server's overall resources and installation details. Still, that limit is likely to support hundreds or thousands of data points. When your resource limits are reached, it may be that the only tell-tale behavior will be a graph that never appears.
If you use Graphist from a publicly acessible location, your installation of it can be called by anyone from anywhere on the web for their own use. This may not be much of a practical issue but the possibility exists. Graphist includes a less-than-foolproof feature to prevent such use or, if you prefer, to allow it.
Known Bugs
There are no known bugs.
