Practical Predictive Analytics

Generating the cluster plot

We will use the clusplot package from the cluster library to plot the cluster assignments based upon the first two principal components. If you recall, principal components are a way to reduce the number of variables in this exercise to two, mainly so that we can graph it on a two-dimensional x and y axis.

If you run the following command, you will see that the first component is a measure of the price and number of units bought, and the second component is a measure of time since the last purchase. That is what is represented on the x and y axis. This is trivial for this case since the cluster model only has three variables as input, but becomes more important as the number of variables you use increases: prcomp(append.clust[,c(3,4,6)], ...