R in a Nutshell, 2nd Edition

Conventions Used in This Book

The following typographical conventions are used in this book:

Italic

Indicates new terms, URLs, email addresses, filenames, and file extensions.

Constant width

Used for program listings as well as within paragraphs to refer to program elements such as variable or function names, databases, data types, environment variables, statements, and keywords. (When showing input and output on the R console, I use constant width text to show prompts and other information produced by the R interpreter.)

Constant width bold

Shows commands or other text that should be typed literally by the user. (When showing input and output on the R console, I use constant width bold text to show you what I typed, including comments.)

Constant width italic

Shows text that should be replaced with user-supplied values or by values determined by context.

Note

This icon indicates a tip, suggestion, or general note.

Caution

This icon indicates a warning or a caution.

In this book, I will sometimes show commands that I entered on my operating system prompt (i.e., in a Bash shell on Linux), and sometimes show commands that I entered in the R console. For commands that I entered in the operating system shell, I use a $ character to show the prompt; for commands entered in the R console, I will use > or + to show the prompt. (In either case, don’t type the prompt character.)