Tableau Consultant @ The Information Lab.... this is my personal blog.

Tim Ngwena

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Tableau Design Month

It's Tableau design month again and to kick it off, Tableau have asked the viz community to do their own take on the recent David McCandlees visualisation on "The World's Biggest Cash Crops"

With that in mind, and with Tableau and Alteryx to hand, I got working on my own entry. Here it is.


Let drugs not be the focus here.

I wanted to focus in more on the rest of the crops on the chart. Whilst all items in the original visualisation were crops, it sort of felt like the visualisation was actually telling more of a story about how lucrative drugs were rather than focusing on everyday crops we're used to hearing about. With that in mind, I've filtered out the the drugs by default but you can add them back in by using the drop down filter at the top. 


Lets make it easier to compare crops against each other

The second thing I wanted to do was to allow you to compare all the main metrics of a particular crop with another crop. I found the circles a little hard to compare and having a separate bar charts all sorted by one measure also made that harder, increasing the number of places you had to look to get an overview. What if you could do all that on one chart? It's a great thing there's a great series of posts on radial charts over at The Information Lab blog (part 1part 2 and part 3). I also built my own slightly different grid / axis using circles rather than a pentagon in Adobe Illustrator. You can grab it too just by saving the image below. It's a PNG image so if you'd like a white version, just invert it in any image editing software or even Powerpoint and off you go.


Lets see if we can see some trends.

The last thing I wanted to do was to make it easier to see trends and so instead of just doing a radar chart which typically don't have filled shapes, I used the dual axis function in Tableau to create a polygon. This then allowed me to see the crops as shapes and as such compare crops with the same general shapes. e.g. if you just keep wheat, rice, barley and maize you can see they have the same general shape but in different scales. The same is true with palm, vegetables, potatoes and cassava. The drugs are on a scale of their own.  


How I used Tableau and Alteryx

Tableau doesn't natively support radar charts but at the end of the day radar charts work on a two dimensional plain so they can be plotted on an x and y grid if you just figure out the math behind it and give each axis a consistent measure. In this case I scored the performance of each crop against the best crop in that measure (not including drugs) and gave it a score out of 10. To speed this up a little I put the base calculations in Alteryx and got it to do the math and the data shaping in about 5 minutes of work. 


Grab everything I used and did for this viz

In the spirit of sharing, here's a zip file of everything I used and did to make this visualisation. Tableau and Alteryx both have trials and free versions that you can use to play around with. Any questions just ask below.