Imagine you’re a budding chef. A data-curious one, of course, so you start by taking a set of foods (pizza, salad, spaghetti, etc.) and ask 10 friends how much of each they ate in the past day. Your goal: to find natural groups of foodies, so that you can better cater to each cluster’s tastes. For example, your fratboy friends might love wings and beer, your anime friends might love soba and sushi