Here is an example interactive coverage map showing the % of water points which are functioning in several regions of Tanzania
(The data displayed below is for illustrative purposes only)
What am I looking at?
This map is what is called a heat map which means that a value from the data in the source file is used to calculate how dark, or light, to make the colour representing that value. In the map above if 100% of the water points in a region were operational it would appear very dark green. If only 10% of the water points were working then it would appear very light green.
The map is interactive and if you hold your mouse over a region, the percentage of water points which are functional in that region will appear alongside the name.
How does it work? This data is generated dynamically, which means that as you change the data in the source file (in this case hosted on Google Fusion Tables) the details appearing on the map will also change. So, if you update the % of functioning water points in a certain region, the updated value and the appropriately shaded boundary will automatically appear on the map.
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