Online commerce sites often show a selection of items below the one you’re after, with a caption something like “People who bought this item also bought…” It’s a marketing ploy, the aim being to encourage you to buy something else while you’re visiting the site. It also suggests an interesting question: what product combinations are bought most and least frequently by individual shoppers? Here’s a command-line approach to this question.

Source: LXer – Online shopping and a one2many tweak