What do . (dot) and % (percentage) mean in R?
问题 My question might sound stupid but I have noticed that . and % is often used in R and to be frank I don't really know why it is used. I have seen it in dplyr (go here for an example) and data.table (i.e. .SD ) but I am sure it must be used in other place as well. Therefore, my question is: What does . mean? Is it some kind of R coding best practice nomenclature? (i.e. _functionName is often used in javascript to indicate it is a private function). If yes, what's the rule? Same question for %