Logarithmic Axes for ExtJS Charts

ExtJS includes a number of nice charting options. I mean, it’s no HighCharts or D3, but it’s not bad. But – it can’t do a logarithmic axis.

A logarithmic axis is useful for displaying data with a large range of values. Sometimes these values are already on a log scale – e.g. the Richter scale is a log scale, as is decibels. You can plot this on a normal linear numeric axis. But sometimes your values can’t be easily converted to a log scale. Maybe you’re plotting wealth distribution. Or, in my case, particle size distributions, where the sizes can range from metres down to microns. When dealing with something like this, you need a log axis.

Fortunately, you can extend ExtJS, and add your own axis implementation. So I built one. You can see the result over at the Sencha Fiddle site.

numeric_vs_log

You can get the code out of the fiddle, or from my github account

 

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Author: Robert Watkins

My name is Robert Watkins. I am a software developer and have been for over 18 years now. I currently work for people, but my opinions here are in no way endorsed by them (which is cool; their opinions aren’t endorsed by me either). My main professional interests are in Java development, using Agile methods, with a historical focus on building web based applications. I’m also a Mac-fan and love my iPhone, which I’m currently learning how to code for. I live and work in Brisbane, Australia, but I grew up in the Northern Territory, and still find Brisbane too cold (after 16 years here). I’m married, with two children and one cat. My politics are socialist in tendency, my religious affiliation is atheist (aka “none of the above”), my attitude is condescending and my moral standing is lying down.

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