We can add more controls to the graph.
nbreaks = 6,
low = "steelblue",
mid = "white",
high = "darkred",
geom = "circle")
- nbreaks=6: break the legend with 6 ranks.
- low = "steelblue": Use lighter colors for negative correlation
- mid = "white": Use white colors for middle ranges correlation
- high = "darkred": Use dark colors for positive correlation
- geom = "circle": Use circle as the shape of the windows in the heat map. The size of the circle is proportional to the absolute value of the correlation.