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
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