Visualizing with Heatmaps in R

Anisa Dhana shows how you can create a quick heatmap plot in R:

To give your own colors use the scale_fill_gradientn function.
ggplot(dat, aes(Age, Race)) +
geom_raster(aes(fill = BMI)) +
scale_fill_gradientn(colours=c("white", "red"))

This is a quick example using ggplot2 but there are other heatmap libraries available too.