Conventions

In this book, you will find a number of styles of text 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: "We can include other contexts through the use of the include directive."

A block of code is set as follows:

# create data frame
df <- data.frame(
  name = c("Wade", "Steve", "Slade", "Bruce"),
  age = c(28, 85, 55, 45),
  job = c("IT", "HR", "HR", "CS")
)

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "selecting them from the Add filters... option box".