[Data Visualization Application] Draw a bivariate mapping map (with R language code)

Bivariate Choropleth Map

When drawing maps, we often use a single variable for mapping processing. Of course, the results displayed in this way can well represent the changes or specific conditions of the characteristics we study (such as income, housing prices, etc.), as shown in the following figure:

single variable map

First, let's briefly explain the meaning of the bivariate mapping by using the following figure:

1. First we create a 3-level sequential color palette with a single variable. The palette starts with lighter neutrals, representing the minimum value of the first variable. Hue colors gradually darken and saturate toward hues that represent higher values. The intermediate color should have the same hue as the base color, but it should be less saturated and brighter, as follows:

   

2. According to the first step, we create another color system, the color meaning of the color system is similar, as follows:

                                   

   

3. We will rotate and stretch the selected 6 colors to obtain the following effects: