The following typographical conventions are used in this book:
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.
- Constant width text that is prefaced with
#>represents output from R.
Constant width bold
Shows commands or other text that should be typed literally by the user.
- Constant width italic
Shows text that should be replaced with user-supplied values or by values determined by context.
This icon signifies a tip, suggestion, or general note.
This icon indicates a warning or caution.