/Crystal Lewis

Let's Talk About Joins tl;dr: “In general, there are two ways to link our data, horizontally or vertically. When linking or joining data horizontally we are matching rows by one or more variables (i.e., keys), making a wider dataset. When joining vertically, column names are matched and datasets are stacked on top of each other, making a longer dataset. Joins can be done in many different programs (e.g., SQL, R, Stata, SAS). Most of this post will be applicable to any language, but examples in R will be provided.”

featured in #481