Data understanding and preparation

Let's start with loading the R packages that we will need for this chapter. As always, make sure that you have installed them first:

> library(cluster) #conduct cluster analysis
> library(compareGroups) #build descriptive statistic tables
> library(HDclassif) #contains the dataset
> library(NbClust) #cluster validity measures
> library(sparcl) #colored dendrogram

The dataset is in the HDclassif package, which we installed. So, we can load the data and examine the structure with the str() function:

> data(wine)

> str(wine)
'data.frame':178 obs. of  14 variables:
 $ class: int  1 1 1 1 1 1 1 1 1 1 ...
 $ V1   : num  14.2 13.2 13.2 14.4 13.2 ...
 $ V2   : num  1.71 1.78 2.36 1.95 2.59 1.76 1.87 2.15 1.64 1.35 
       ...
 $ V3   : num  2.43 2.14 2.67 2.5 2.87 2.45 2.45 2.61 2.17 2.27 ...
 $ V4   : num  15.6 11.2 18.6 16.8 21 15.2 14.6 17.6 14 16 ...
 $ V5   : int  127 100 101 113 118 112 96 121 97 98 ...
 $ V6   : num  2.8 2.65 2.8 3.85...