Introducing content-based recommendation

To understand the inner workings of a content-based recommendation system, let's look at a simple example. We will use the wine dataset from https://archive.ics.uci.edu/ml/datasets/wine. 

This dataset is the result of the chemical analysis of wine grown in the same region in Italy. We have data from three different cultivars (From an assemblage of plants selected for desirable characters, Wikipedia: https://en.wikipedia.org/wiki/Cultivar).

Let's extract the data from UCI machine learning repository:

> library(data.table)
> wine.data <- fread('https://archive.ics.uci.edu/ml/machine-learning-databases/wine/wine.data')
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