R Tutorial : Why you should use functions

Want to learn more? Take the full course at https://learn.datacamp.com/courses/introduction-to-writing-functions-in-r at your own pace. More than a video, you'll learn hands-on coding & quickly apply skills to your daily work. --- Hi, I'm Richie from DataCamp. You've already used many of R's functions. If you've taken any other DataCamp courses, I'm sure you had to call mean in some of the exercises. To recap, it has three arguments. x is a vector of numbers or times. trim is the proportion of highest and lowest values to remove before calculation. na-dot-rm is a logical value determining whether missing values should be removed. When you call mean (or any other function), there are several ways you can pass arguments to it. Firstly, you can pass arguments by position. Here, R knows that numbers is the x argument, zero-point-one is the trim argument, and TRUE is the na-dot-rm argument. One problem is that it can be hard to remember what each variable is. Secondly, you can pass arguments by name. In this case, the order doesn't matter, though it's harder to read when the arguments are ordered unconventionally. Most code style guides suggest a combination approach: pass the arguments in the same order as the documents specify them, and provide names for rarer arguments but not common ones. There are thousands of functions available in R packages, so you might be wondering, "why should I write my own?". Let me show you a case study. Imagine you are analyzing the scores of a geography test. First, you import the data. Then you look at the data, and like almost every dataset, it has a load of columns that you don't care about, so you just select the columns you need: the student's name, when they took the test, and the score they got. Great work! You're ready to science some data! Suppose you aren't just analyzing geography test scores, you are also analyzing the scores for English, art, and Spanish. No problem, all you have to do is to copy and paste the c