R: Data Analysis and Visualization

Creating heat maps of a single Z variable with a scale

In this recipe, we will make a heat map that shows the variation in values of one variable (z) along the x and y axes as a grid of colors and display a scale alongside.

Getting ready

We will only use the base graphics functions for this recipe. So, just open up the R prompt and type in the following code. We will use the sales.csv example dataset for this recipe. So, let's first load it:

sales<-read.csv("sales.csv")

We will use the RColorBrewer package for some good color palettes. So, let's make sure that it's installed and loaded:

install.packages("RColorBrewer")
library(RColorBrewer)

How to do it...

The sales dataset has monthly sales data for four cities. Let's make a heat map with the months ...