Maps and Location - Communicating Data with Tableau - page 223

Adding a Second Encoding
We've encoded population with circle size, but we haven't used color yet. We could use the
Population Density calculated field to make circles darker proportionate with the number of
people per square mile. This would be a very intuitive thing to do, as we naturally identify
darker colors with more and lighter colors with less. By now you get it: it's as easy as drag-
ging the Population Density field to the Color shelf. The resulting view is shown in Fig-
ure 10-5 .
Figure 10-5. Circle maps with two encodings: size and color
Now we can make a number of different comparisons. It's more complex, but also more use-
ful if we invest the time to learn the map. While there are fewer people in New York County