Re: Auto-generating a graphs Y scale

At 10:01 AM +0100 8/25/08, Richard Heyes wrote:

Can anyone give me some pointers for auto generating an appropriate Y scale for a graph (eg a bar/line graph). Much like JPGraph does. Thanks. -- Richard Heyes

Richard: First, the y scale is the one that runs up and down and not right to left. :-) Second, the physical length of the y scale should be static and whatever you want it to be (i.e., 5 inches, 10 inches, etc.). Third, to plot points along this axis simply take the maximum value found in their Y coordinate and divide that into the physical length of the Y scale, such as 10 inches/1500. That will give you a delta value by which you can multiply all values to get their position on the y scale. Do the same for x, and you have a scatter graph. Do the same for x, sort x, connect the dots and you have a line graph. Do the same for x and provide a range for x and you have a bar chart. Here's an example: http://webbytedd.com/aa/stdev/ At least I think that's what you're asking. Cheers, tedd -- ------- http://sperling.com http://ancientstones.com http://earthstones.com