This will default the reporter to , require the library, and as the interface. With this, you may then invoke with additional arguments, here enabling support, and changing the reporter to :To skip tests in this manner, use in a “before” hook:
So, to start off with the basics, here's what I'd suggest you keep in mind for now: R has multiple data types. Some of them are especially important when doing basic data work. And some functions that are quite useful for doing your basic data work require your data to be in a particular type and structure.A matrix needs to have all the same data type in every column, such as numbers everywhere.
In a data frame, you can think of each row as similar to a database record and each column like a database field. There are lots of useful functions you can apply to data frames, some of which I've gone over in earlier sections, such as summary() and the psych package's describe().There are several as() functions for converting one data type to another, including as.character(), as.list() and as.data.frame().
When you define a generic class, you can apply restrictions to the kinds of types that client code can use for type arguments when it instantiates your class. If client code tries to instantiate your class by using a type that is not allowed by a constraint, the result is a compile-time error. These restrictions are called constraints. Constraints are specified by using the contextual keyword. The following table lists the six types of constraints: The use of a generic type parameter as a constraint is us