A demo of a logarithmic Bar chart

Summary: When you have a dataset which has wildly different values in it a logarithmic chart like this may be the answer.

[No canvas support]

At first look you may think that this looks like a regular, basic Bar chart. And you'd not be far wrong. The Y axis has six labels instead of five (not including zero) but apart from that what's different?

The scale - that's what. Notice that instead of being a linear progression of (for example) [0, 2, 4, 6, 8, 10] it's a logarithmic scale which has the numbers [0,10,100,1000,10000,100000,1000000].

This can make it easier to show datasets which have one or more data points that are significantly higher than the rest - as is shown here (the first value is 1,000,000 and the second value is 5. The entire dataset is:

[1000000,5,6,4,6,8012,12,7]

Before the chart is created the data is converted to a smaller numbers by using the RGraph.log() API function. It's these smaller numbers which are then plotted on the chart.


This goes in the documents header:
<script src="RGraph.common.core.js"></script>
<script src="RGraph.line.js"></script>
Put this where you want the chart to show up:
<canvas id="cvs" width="600" height="250">
    [No canvas support]
</canvas>
This is the code that generates the chart: