Generate a color array.Fill the gene then generate the legend.
wp_bgfill(
p,
value,
high = "red",
low = "blue",
legend = TRUE,
legend_x = 0.001,
legend_y = 0.94
)A 'wpplot' object
p is
value is the amount of expression.
The color of highest gene.
The color of lowest gene.
Whether you need legend.
horizontal position of the legend
vertical position of the legend