Vectors
The fundamental R data structure is the vector, which stores an ordered set of values called elements. A vector can contain any number of elements. However, all the elements must be of the same type; for instance, a vector cannot contain both numbers and text.
There are several vector types commonly used in machine learning: integer (numbers without decimals), numeric (numbers with decimals), character (text data), or logical (TRUE or FALSE values). There are also two special values: NULL, which is used to indicate the absence of any value, and NA, which indicates a missing value.
It is tedious to enter large amounts of data manually, but simple vectors can be created by using the combine function c(). The vector can also be given a name using the arrow <- operator, which is R's assignment operator, used in a similar way to the = assignment operator in many other programming languages.
For example, let's construct a set of vectors containing data on three medical patients. We'll...
