2

VECTORS

The fundamental data type in R is the

vector. You saw a few examples in Chap-

ter 1, and now you’ll learn the details. We’ll

start by examining how vectors relate to some

other data types in R. You’ll see that unlike in languages

in the C family, individual numbers (scalars) do not

have separate data types but instead are special cases

of vectors. On the other hand, as in C family languages,

matrices are special cases of vectors.

We’ll spend a considerable amount of time on the following topics:

Recycling The automatic lengthening of vectors in certain settings

Filtering The extraction of subsets of vectors

Vectorization Where functions are applied element-wise to vectors

All of these operations are central to R programming, and you will see
them referred to often in the remainder of the book.