It's important to learn to create heatmaps, but it's even more important to know how to interpret them!
We've plotted the burtin dataset from the Vega datasets. It shows us how 16 different kinds of bacteria are affected by three different antibiotics: Penicillin, Streptomycin, and Neomycin. Here's a heatmap of the correlation between the amount of each drug:
Which pair has the highest correlation value?