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Making your thematic map
Are you ready to build some maps? We can do this without the use of GeoServer since we have not yet discussed how to install it; we will cover that in the next chapter. For the moment we will play with an online map engine to assist your understanding of thematic map concepts:
- First, download the WorldBank.csv file from the Packt site. This file contains a set of economic data already prepared for you. The data comes from the World Bank and was preprocessed to let you focus on the thematic map:
The World Bank is an international financial institution that provides loans to countries of the world for capital programs. It also distributes a lot of social and economic data under an open data license. The data used in this section is available at http://datacatalog.worldbank.org/.
- To build the thematic map, we will use an online engine. Although it's built on open source software, it's a commercial solution. You need to register to use it, but, for the purpose of this section, and for other small maps you may want to create, you can use the free of charge account. Point your browser to https://carto.com/:
- Click on the Sign up link from the home page and complete your application for a free of charge account. After signing up, log in to Carto and you will arrive at the front dashboard, the starting point for building your maps:
- Select the WorldBank.csv file and drag it on the dashboard to create your first map. The engine will process your data, trying to georeference it, and then a new map will be shown for you:
- The map you just created does not seem interesting. All the countries use the same orange symbol, what about the economic data from World Bank? Locate the toolbar in the right part of the user interface and press the symbol with a paintbrush; this will show you a custom interface to change the rendering of your data:
- Select the choropleth category and leave the other setting at default. Now your map shows the countries with a color ramp, according to the GDP value. You can explore the setting; try to change the classification and the color ramp used:
You built a brand new thematic map, selecting data and symbol colors. You will need to set these parameters exactly in GeoServer to produce beautiful maps. This time we did it without exploring the technical details behind feature rendering. In Chapter 6, Styling Your Layers, you will learn how to use SLD (Styled Layer Descriptor) to make thematic maps.