7

R PROGRAMMING STRUCTURES

R is a block-structured language in the man-

ner of the ALGOL-descendant family, such

as C, C++, Python, Perl, and so on. As you’ve

seen, blocks are delineated by braces, though

braces are optional if the block consists of just a single

statement. Statements are separated by newline char-

acters or, optionally, by semicolons.

Here, we cover the basic structures of R as a programming language.

We’ll review some more details on loops and the like and then head straight

into the topic of functions, which will occupy most of the chapter.

In particular, issues of variable scope will play a major role. As with many

scripting languages, you do not “declare” variables in R. Programmers who

have a background in, say, the C language, will find similarities in R at first

but then will see that R has a richer scoping structure.

7.1 Control Statements..........................................................

Control statements in R look very similar to those of the ALGOL-descendant

family languages mentioned above. Here, we’ll look at loops andif-else

statements.