Conventions

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows. Any command-line input or output is written as follows:

cor(x1, y1) #correlation of x1 and y1
[1] 0.8164205

> cor(x2, y1) #correlation of x2 and y2

[1] 0.8164205

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: Clicking the Next button moves you to the next screen.