Click to learn more about co-author Rosaria Silipo.
Click to learn more about co-author Paolo Tamagnini.
Today we want to draw the choropleth map as shown above. So, what do we need?
- A map of the countries of the world and the corresponding numbers of their populations
Our dataset is the CSV file population2013.csv, and it contains a list of 214 world countries with their corresponding population numbers as of 2013.
The getScript() method from jQuery is great to load a single JS library. However, when more concurrent, possibly dependent, JS libraries are needed, other load methods might be more suitable. We will talk about those in another post. Stay tuned!
Also, note that we have defined a heat map going from light blue (least populated countries) to dark blue (most populated countries).
It is common practice to use a monochromatic color scale. We chose the scale from light blue to dark blue, as recommended on the Color Brewer 2.0 website.
In order to appreciate the differences in population a bit better, we could use a logarithmic scale. In this case, a Math Formula node calculates log(2013) for each country to append to the original dataset.
|1||<h1><font color=”gray”>Population in logarithmic numbers by world countries in 2013</font></h1>|
Indeed, now, if we right-click the metanode and select its “Interactive View” item, we can see the same choropleth map with a gray title, exactly as in Figure 1. Also, if we execute the workflow from our WebPortal, the final web page will also contain this interactive view with choropleth and title.
Again, if running on a WebPortal, this composite view translates into a web page with multiple choropleths and titles.
The final workflow is shown in Figure 5 and is also available on the EXAMPLES server under 03_Visualization/04_Geolocation/07_Choropleth_World_Map.
Summary and Next Steps
The workflow is available on the EXAMPLES server under 03_Visualization/04_Geolocation/07_Choropleth_World_Map.