25.2. Generating Graphs on the Fly
Perhaps a more likely use of dynamic graphics is in generating graphs. Since graphs rely on data, they lend themselves to formula-driven creation. If the data change often, using PHP to generate the graphs is a good idea. In the following examples, I've written the data into the script, but pulling data from a database is not difficult. Sending the data from a form is probably not a practical idea for large amounts of data. The GET method imposes a relatively small limit on the total size of a URL that varies between Web servers. You could use the POST method, however. The two examples I'll show are a bar graph and a pie chart. Each uses the same set of data, which is a fictitious survey of favorite meat.
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